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Prepared by the Bureau of Ships 



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For sale by the Superintendent of Documents, 
U. S. Government Printing Office 
Washington 25, D. C. 

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Diesel Engine Maintenance Training Manual — U. S. Navy has been written to fill the need in Navy training 
schools for a practical text on the subject, to provide for continued later training, and to guide those concerned 
in trouble shooting aboard ship and at shore bases. It is intended to complement Fundamentals of Diesel Engines — 
U.S. Navy. 

The latter publication explains the principles of the diesel engine; and the purpose and function of engine 
systems, component parts, and accessories. This publication continues the subject into the field of actual engine 
operation. It explains the methods of preventing or detecting operating irregularities and casualties, the 
maintenance and repair of specific equipment, and the best or recommended mechanical practices applicable. 

This manual will be of particular value when used to supplement the regular training courses in all classes 
of diesel schools. Rarely during this type of training are irregularities or casualties encountered in the equip- 
ment under study. This applies particularly to those troubles that develop progressively. They must be simu- 
lated or introduced by the instructor. Time and equipment limitations do not permit a comprehensive study, in 
the school laboratories, of the innumerable items in the maintenance and casualty repair field. 

Lack of knowledge or experience in caring for these items, many of them minor and obscure, contributes in 
large measure to the air of mystery which persists in surrounding the engine in some quarters and to the unneces- 
sary casualties and loss of power. This publication will serve as a source of additional information, enabling 
the trainee to perform his engine room duties more competently. 

This publication will be equally valuable aboard ship and at shore stations in further training, and for refer- 
ence purposes by qualified personnel. When so used it will in no sense supersede the various instruction manuals 
and technical directives issued by the Bureau of Ships. The manuscript, prepared by the Bureau of Ships and 
based upon that bureau's large store of operating data and experience, may be described justly as an over-all 
discussion of that store of data and experience. 

Chapter 1 presents a concise trouble shooting guide and provides the engine operator with sound general 
procedures to be followed in locating the causes of faulty engine operation. 

The remainder of the book discusses troubles most likely to be encountered in diesel operation. Trouble 
causes are enumerated according to the various engine systems, along with the proper preventive measures to 
forestall their happening, and the proper repair methods if the troubles do happen. The preventive measures 
cannot be too highly stressed. The diesel engine, if properly maintained, should be relatively as trouble free 
as any comparable high grade machine. 


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Chapter 1. Troubles: Thbir Symptoms and Thbir Causbs 
A. General Trouble Shooting Procedure 


Recognizing and locating troubles 

B. Engine 

Fails to Starr 


Engine will not crank but can be barred over 


Engine cannot be cranked and cannot be 


C. Unusual or Erratic Operation 



Engine stops suddenly 


Engine overspceds 


Engine will not carry load (loss of* power). 


Engine will not shut off 




Cylinder safety valves pop frequently during 

engine operation 


Engine will not reach rated speed 


Engine hunts (speed varies at constant 

throttle setting) 

D. Noises 

1D1. Pounding 

1D2. Knocking 

1D3. Metallic clicking 

1D4. Rattling 

E. Instruments — Pressure 

1E1. Low lube oil pressure 

1E2. High lube oil pressure 

1E3. Low fuel oil pressure (in low-pressure fuel 

supply system) 

1E4. Low cooling water pressure (fresh) 

1E5. Low cooling water pressure (salt) 

1E6. High cooling water pressure (salt) 

1E7. Low compression pressure 

1E8. Low firing pressure 6 

1E9. High firing pressure 6 

1E10. Low scavengi ng air receiver pressu re (super- 
charged engine) 6 

1E11. High exhaust back pressure 6 

R Instruments — Temperature 

1F1. Low lube oil temperature 6 

1F2. High lube oil temperature 6 

1F3. Low cooling water temperature (fresh) 6 

1F4. High cooling water temperature (fresh). . . 6 

1F5. Low cylinder exhaust temperature 7 

1F6. High exhaust temperature in one cylinder.. 7 

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G. Instruments — Correlation of Cylinder Exhaust Tem- 

perature and Cylinder Firing and Compression 

1G1. Low firing pressure and low exhaust 

temperature 7 

1G2. Low firing pressure and high exhaust 

temperature 7 

1G3. High firing pressure and low exhaust 

temperature 7 

1G4. High firing pressure and high exhaust 

temperature 7 

1G5. Low compression pressure and low exhaust 

temperature 7 

1G6. Low compression pressure and high exhaust 

temperature 7 

1G7. High compression pressure and low exhaust 

temperature 7 

1G8. High compression pressure and high ex- 
haust temperature 7 

H. Instruments — Speed 

1H1. Idling speed not normal 7 

1H2. Maximum speed not normal 7 

I. Presence of Smoke 

111. Black exhaust smoke 8 

112. Bluish-white exhaust smoke 8 

113. Smoke arising from crankcase 8 

114. Smoke arising from cylinder head 8 

115- Smoke arising from engine auxiliary equip- 
ment such as blower, pumps, etc 8 

J. Excessive Consumption of Lube Oil, Fuel, or Water 

1J1. Excessive lube oil consumption 8 

1J2. Excessive fresh water consumption 8 

1J3- Excessive fuel oil consumption 8 

K. Contamination of Lube Oil, Fuel, or Water 

1K1. Fuel oil in lube oil 8 

1K2. Water in lube oil 9 

1K3. Oil or grease in water 9 

1K4. Water in fuel oil 9 

1K5. Air or gas in water 9 

1K6. Metal particles in lube oil . 9 

Chaptbr 2. Air Intakb System 
A. Blowers 

2A1. Introduction 11 

2A2. Turbochargers 12 

a. Possible trouble — Damaged shaft or 

thrust bearings 13 

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b. Possible trouble — Damaged turbine 

blading 14 

c. Possible trouble — Damaged nozzle ring . 15 

d. Possible trouble — Damaged blower im- 

peller 16 

2A3. Roots type blowers 17 

a. Possible trouble — Worn gears 17 

b. Possible trouble — Scored rotor lobes and 

casing 18 

c. Possible trouble — Blower shaft oil 

seals leaking 20 

d. Possible trouble — Failure of serrated 

shafts 21 

2A4. Hamilton-Whitfield blowers 21 

B. Air Passages 

2B1. Troubles in air passages 22 

a. Possible trouble — Foreign bodies in 

manifold 22 

b. Possible trouble — Excess accumulation 

of oil in manifold or air box 23 

C. Air Heaters 

2C1. Electrical air heaters 24 

a. Possible trouble — Failure of electric air 

heater to operate 24 

2C2. Flame primers for air heating 25 

a. Possible trouble — Failure of flame primer 

to operate 25 

D. Air Cleaners and Silencers 

2D1. Introduction 25 

2D2. Dry, or viscous type air cleaner and silencers 25 

a. Possible trouble — Clogged and dirty air 

cleaner 26 

b. Possible trouble — Explosion from using 

volatile solvents for cleaning 26 

2D3. Oil bath type air cleaners and filters 26 

a. Possible trouble — Excess oil in cleaner 

causing engine to run away 26 

Chapter 3. Exhaust System 

A. Manifolds 

3A1. Introduction 27 

a. Possible trouble — Cracked manifold .... 27 

B. Silencer 

3B1. Introduction 28 

3B2. Wet type silencers 28 

a. Possible trouble — Back flow of water 

into engine 28 

b. Possible trouble — Corrosion of muffler . . 30 
3B3- Dry type silencers 31 

a. Possible trouble — Excessive accumula- 

tion of oil or soor in the muffler 31 

b. Possible trouble — Baffles or end plates 

broken loose 31 

C. Piping and Stacks 

3C1. Piping 32 

a. Possible trouble — Restricted exhaust 

piping 32 

3C2. Stacks 34 

a. Possible trouble — Corrosion of exhaust 

stack 35 

Chapter 4. Fuel Systems 

Section 1. Transfer Pumps 37 

A. Gear Pumps 

4A1. Introduction 37 

4A2. General description 37 

a. Possible trouble — Leakage at shafts 37 

b. Possible trouble— Insufficient discharge. 39 

B. Vane Pumps 

4B1. General description 39 

a. Possible trouble — Insufficient fuel sup- 
plied to injector pumps 40 

C. Plunger Pumps 

4C1. General 41 

4C2. The Bosch fuel transfer pump 41 

a. Possible trouble — Bosch fuel transfer 

pump fails to operate 41 

4C3. The Excel lo fuel transfer pump 42 

Section 2. Injection Pumps and Nozzles 42 

D. General 

4D1. Functions of the system 42 

4D2. Types of fuel systems 42 

E. Bosch 

4E1. General description 43 

a. Possible trouble — Damaged plunger and 

barrel assembly 45 

b. Possible trouble— External leakage from 

pump 46 

c. Possible trouble — Plunger stuck in 

barrel 47 

d. Possible trouble — Control rack sticky or 

jammed 47 

e. Possible trouble— Delivery valve inop- 

erative 48 

f. Possible trouble — Backlash (looseness 

or play) in control rack 49 

g. Possible trouble — Pump improperly 

timed 49 

h. Possible trouble — Pumps improperly 

calibrated (balanced) 50 

i. Possible trouble — Broken plunger spring 50 
4E2. Spray nozzles and nozzle holders 51 

a. Possible trouble — Nozzle opening pres- 

sure too high 51 

b. Possible trouble — Nozzle opening pres- 

sure too low 55 

c. Possible trouble — Dribbling (leaky) 

nozzle 55 

d. Possible trouble — Distorted nozzle spray 

pattern 56 

e. Possible trouble — Nozzle fails to chatter 57 

f. Possible trouble — Excessive overflow 

from nozzle leakofF connection 57 

g. Possible trouble — Nozzle turns blue 

after service in engine 58 

F. General Motors 

4F1. General description 60 

a. Possible trouble — Damaged plunger and 

bushing 60 

b. Possible trouble — External leakage from 

injector 61 

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c. Possible trouble — Plunger stuck in 

bushing 62 

d. Possible trouble — Rack sticking or 

jammed 63 

e. Possible trouble — Backlash (looseness) 

of rack 64 

f. Possible trouble — Broken plunger spring 64 

g. Possible trouble — Dribbling from spray 

tips 64 

h. Possible trouble — Distorted spray 

pattern 64 

i. Possible trouble — Pop pressure too high 65 
j. Possible trouble — Pop pressure too low. 65 
k. Possible trouble — Injectors not balanced 66 
I. Possible trouble — Injectors improperly 

timed 66 

G. Excel I o Fuel Injection Equipment Type A Pump 

4G1. General description 67 

a. Possible trouble— Pump unbalanced .... 69 

b. Possible trouble — Scored plungers and 

cylinders 70 

c. Possible trouble — Sticking plungers . . . . 70 

d. Possible trouble — System air bound 71 

4G2. Exccllo fuel injection nozzle 72 

a. Possible trouble — Faulty injector nozzles 72 

H. Cummins Fuel System 

4H1. General description 73 

a. Possible trouble — Scored distribution 

disk and cover 75 

b. Possible trouble — Damaged metering 

pump plunger and barrel 77 

c. Possible trouble — Damaged priming 

valve 77 

d. Possible trouble — Sticky injector 

plungers 77 

e. Possible trouble — Worn or scored injec- 

tor plungers 78 

f. Possible trouble — Clogged injector spray 

holes 78 

g. Possible trouble — Worn injector cup tip 78 

I. Atlas Fuel System 

411. General description 79 

a. Possible trouble — Improper timing of 

fuel system 82 

b. Possible trouble — Clogged spray orifices 83 

c. Possible trouble — Leaky nozzle tip 83 

d. Possible trouble — Worn spray valve 

packing 83 

c. Possible trouble — Improper functioning 

of pressure regulating valve 83 

J. Cooper-Bessemer Fuel Injection System 

4J1. General description 84 

4J2. The fuel oil pump 84 

a. Possible trouble — Pump fails to operate 

properly 85 

4J3. The accumulator bottle 86 

4J4. The fuel injector (distributor) 87 

a. Possible trouble — Injector operates im- 
properly 87 

4J5. The fuel injection nozzle 90 

Section 3- Fubl Links 90 

K. Low-Pressure Lines 

4K1. General description 90 

a. Possible trouble — Threaded pipe joints 

breaking at root of threads 90 

L. High- Pressure Lines 

4L1 . General description 91 

a. Possible trouble — Broken high pressure 

fuel lines 91 

Section 4. Filters and Strainers 92 

M. Filters 

4M1. General description 92 

a. Possible trouble — Filter clogged before 

500 hours' operation 92 

b. Possible trouble — Air in filter 94 

c. Possible trouble — Leaky filter case 95 

N. Strainers 

4N1. General description 96 

a. Possible trouble — Broken scraping 

mechanism 96 

Section 5. Tanks 97 

O. Fuel Oil Tanks 

401. Introduction 97 

a. Possible trouble — Leaking tank 97 

b. Possible trouble — Corrosion of tank 

interiors 98 

c. Possible trouble — Suction and vent lines 

rusting through 98 

Chapter 5- Speed Control System 
A. Mechanical Governors 

5A1. Introduction 99 

5A2. General description 99 

5A3. G.M. 71 series mechanical governor 100 

a. Possible trouble — Stripped splines on 

governor drive shaft 100 

b. Possible trouble — Broken high or low 

speed springs 101 

c. Possible trouble — Excessive wear of 

governor parts or external linkage .... 101 

d. Possible trouble — Binding in governor 

or linkage 101 

c. Possible trouble — Low speed spring 

tension improperly adjusted 102 

f. Possible trouble — High speed spring 

tension ad justment improper 103 

g. Possible trouble — Improper gap clear- 

ance 103 

h. Possible trouble — Buffer screw adjust- 

ment improper . 103 

5A4. Pierce mechanical governor 103 

a. Possible trouble — Broken or loose fly- 

balls 104 

b. Possible trouble — Worn shaft bearings . . 105 

c. Possible trouble — Worn thrust sleeve 

face 105 

d. Possible trouble — Improper adjustment 

of pump control rod positioning screw 105 

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c. Possible trouble — Improper adjustment 
of speeder spring tension 

f. Possible trouble — Improper adjustment 

of speed droop 

g. Possible trouble — Stickiness in governor 

or external linkage 

h . Possible trouble — Stripped or worn drive 


B. Hydraulic Governors 

5B1. Introduction 

5B2. Sources of information 

a. Possible trouble — Low oil level 

b. Possible trouble — Stickiness of governor 

mechanism or linkage 

c. Possible trouble — Governor improperly 


d. Possible trouble — Damaged drive shaft. 

e. Possible trouble — Drive gear clearance 


f . Possible trouble — Leaky oil seals 

g. Possible trouble — Foaming of governor 


C. Overspeed Safety Devices 

5C1. Introduction 

5C2. Types of speed governors 

a. Possible trouble — Trip operates below 

specified tripping speed 

b. Possible trouble — Trip fails to operate 

at specified tripping speed 

Chapter 6. Lubricating System 

A. Lube Oil Pumps 

6A1. Introduction 

a. Possible trouble — Lube oil pump failures 

B. Oil Coolers 

6B1. Introduction 

a. Possible trouble- -Excess scale on cooler 


b. Possible trouble—Leakage of oil tubes . . 

c. Possible trouble—Corroded zinc plugs 

and plates 

C. Valves 

6C1. Introduction 

6C2. Line valves 

a. Possible trouble — Leaking valve (globe 

and angle valves) 

b. Possible trouble — Leaking valve (gate 


c. Possible trouble — Leaking valve stems. 
6C3. Check valves 

a. Possible trouble — Leaking check valves 
6C4. Pressure regulating valves 

a. Possible trouble — Defective pressure 

regulating valve 

6C5. Temperature regulating valves 

D. Oil Lines and Passages 

6D1. Cleanliness 

a. Possible trouble — Plugged lube oil lines 

b. Possible trouble — Cracked lube oil lines 

E. Centrifuges, Strainers , Filters 

6E1. Introduction 

Page Page 

6E2. Centrifuges 133 

106 a. Possible trouble — Oil discharged from 

water outlet 133 

106 b. Possible trouble— Bent shaft 133 

c. Possible trouble — Failure to use and to 

107 clean 133 

6E3. Strainers 134 

107 Possible trouble — Broken scraping 

mechanism 134 

107 6E4. Filters 134 

10g a. Possible trouble — Filter clogged pre- 

108 maturely 135 

109 Chapter 7. Cooling System 

A. General 

110 7A1. Introduction 137 

112 B. Heat Exchangers 

7B1. General 137 

115 7B2. Harrison type cooler 138 

115 a. Possible trouble — Excessive scale on 

cooler element 138 

116 b. Possible trouble — Clogged cooler cle- 

ment 139 

U5 c. Possible trouble — Leaky cooler 140 

llg 7B3. She 11 -and -tube type 140 

a. Possible trouble — Excessive scale de- 
ny posit on cooler tubes 141 

b. Possible trouble — Clogged cooler elc- 

118 ment 141 

c. Possible trouble — Leaky cooler 141 

C. Pumps 

7C1. General 141 

121 7C2. Centrifugal pumps 141 

a. Possible trouble — Insufficient discharge. 142 

b. Possible trouble — Scored shaft or shaft 

121 sleeve 143 

c. Possible trouble — Broken shaft 144 

123 d. Possible trouble — Clogged impeller 144 

126 c . Possible trouble — Worn or broken im- 

peller 144 

127 f. Possible trouble — Corrosion of pump 

parts 146 

128 g. Possible trouble — Shaft seals worn 146 

128 h. Possible trouble — Poor condition of 

shaft bearings 147 

128 j. Possible trouble — Excessive wear of 

wear rings 147 

130 7C3. Gear pumps 147 

130 a. Possible trouble — Insufficient discharge 147 

131 b. Possible trouble— Scored shaft 148 

131 c. Possible trouble — Broken shaft 148 

131 d. Possible trouble — Damaged pumping 

gears 149 

131 e. Possible trouble — Corrosion of pump 

131 parts 150 

f. Possible trouble — Shaft seals worn 1 50 

132 g. Possible trouble — Poor condition of 

132 shaft bearings 150 

132 D. Valves 

7D1. General 150 

133 7D2. Manually operated valves: general 151 

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7D3. Manually operated valves; lubricated plug 

type 151 

a. Possible trouble — Valve improperly 

lubricated 151 

7D4. Thermostatic valves: general 152 

7D5. Thermostatic valves : automatic temperature 

regulators 152 

a. Possible trouble — Valve improperly ad- 
justed 152 

7D6. Thermostatic valves: automotive type 

thermostat 154 

a. Possible trouble — Inoperative thermo- 
stat 154 

E. Passages and Piping 

7E1. General 155 

7E2. Passages 155 

a. Possible trouble — Excessive scale forma- 

tion in passages 156 

b. Possible trouble — Corrosion of cooling 

water passages 156 

c. Possible trouble — Leaky cooling pas- 

sages 156 

7E3- Piping 157 

a. Possible trouble — Clogged water line . . . 158 

b. Possible trouble — Leaky water piping. . 158 

F. Strainers 

7F1. General 161 

a. Possible trouble — Clogged strainer 

basket 161 

b. Possible trouble— Corroded strainer 

basket 162 

Chapter 8. Starting Systems 

A. Introduction 

8A1. General 163 

B. Electrical Starting Systems 

8B1. General 163 

a. Possible trouble — Dirty commutator... 163 

b. Possible trouble Burned brushes 164 

c. Possible trouble — Weak insulation 164 

C. Air Starting Systems 

8C1. General 165 

8C2. Compressor 166 

a. Possible trouble — Compressor over- 

heating 166 

b. Possible trouble — Excessive belt wear . 166 

c. Possible trouble — Squeaking V-bclts . 167 
8C3- Receiver or tank . 167 

a. Possible trouble -Sticking safety valve . 167 

8C4. Timing mechanisms: general 167 

8C5. Timing mechanisms: direct mechanical lift 

type 167 

a. Possible trouble — Improper adjustment 167 
8C6. Timing mechanisms: rotary distributor — . 168 
a. Possible trouble— Inoperative dis- 
tributor 168 

8C7. Timing mechanisms: plunger type distribu- 
tor valves 168 

a. Possible trouble — Stuck distributor 

valves 168 

8C8. Air starting valves 169 


a. Possible trouble — Air valve sticking 

open — air actuated 169 

b. Possible trouble — Leaking air valve 

— mechanical lift 170 

Chapter 9. Electrical Systems 

A. Storage Batteries 

9A1. General 171 

a. Possible trouble — Dead battery 172 

b. Possible trouble — Rapid loss of electro- 

lyte level 174 

c. Possible trouble — Co osion of battery 

terminals 175 

d. Possible trouble — Burned terminals 175 

e. Possible trouble — Battery explosion ... 176 

B. Generators and Generator Control 

9B1. Generators 177 

a. Possible trouble — Generator not charg- 
ing — defective generator 177 

9B2. Generator controls 179 

a. Possible trouble — Generator improperly 

charging — control unit defective ... . 179 

C. Relays and Contactors 

9C1. General 181 

a. Possible trouble — Burned contacts 181 

b. Possible trouble — Magnetic device fails 

to engage pinion and close circuit 182 

D. Wiring 

9D1. General 182 

a. Possible trouble — Burned insulation 182 

b. Possible trouble — Short circuits 183 

E. Electrical Remote Control Devices 

9E1. General 183 

9E2. A.C. Sclsyn motor 184 

a. Possible trouble — no response to changes 

of transmitter 184 

9E3. D.C. Selsvn motor 185 

a. Possible trouble — Sclsyn fails to operate 185 

9E4. A.C, D C. split field motor 185 

a. Possible trouble — Motor fails to operate 185 

b. Possible trouble — Slip coupling too 

loose 186 

Chapter 10. Enginb Frame, Sub-Base, and Mountings 

A. Engine Frame 

10A1. General 187 

a. Possible trouble — Cracked frame 188 

b. Possible trouble— Clogged oil passages. 190 

c. Possible trouble — Excessive scale forma- 

tion in passages 191 

d. Possible trouble — Dirty air passages .... 191 

e. Possible trouble — Crankcasc explosion . . 192 

B. Sub-Base 

10B1. General 194 

a. Possible trouble — Cracked sub-base 194 

b. Possible trouble— Warped sub-base 194 

C. Mountings 

10C1. General 195 

a. Possible trouble — Inoperative vibration 

isolator 197 

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Chaptbr 11. Cylinder Assembly 

A. Introduction 

11A1. General 199 

B. Cylinder Liners 

11B1. General 199 

a. Possible trouble — Cracked or broken 

liner 201 

b. Possible trouble — Scored liner 203 

c. Possible trouble — Obstructed liner ports 204 

d. Possible trouble — Worn liner 205 

C. Cylinder Heads 

11C1. General 208 

11C2. Parts 209 

a. Possible trouble — Cracked cylinder 

head 210 

b. Possible trouble — Burned or corroded 

cylinder head 211 

C. Possible trouble — Distorted cylinder 

head 212 

d. Possible trouble — Fouled combustion 

chamber 212 

D. Cylinder Head Studs 

11D1. General 213 

a. Possible trouble — Stripped or broken 

stud 214 

E. Cylinder Head Gaskets 

11E1. General 217 

a. Possible trouble — Leaky gasket 218 

Chapter 12. Valve Gear 

A. Exhaust Valves 

12A1. Mushroom type valves and assembly 221 

a. Possible trouble — Exhaust valve stick- 

ing open 221 

b. Possible trouble — Burned valves 222 

c. Possible trouble — Broken valve springs 224 

d. Possible trouble — Worn valve keepers 

and retaining washers 225 

e. Possible trouble— Valve head broken off 

valve stem 227 

12A2. Hamilton supercharge valves 228 

a. Possible trouble — Supercharge valves do 

not rotate 228 

B. Intake Valves and Ports 

12B1. Poppet type valves 230 

12B2. Ports 230 

a. Possible trouble — Dirty and clogged in- 
take air ports 230 

C. Rocker Arms and Push Rods 

12C1. Rocker arms 230 

a. Possible trouble — Worn bushings 230 

b. Possible trouble — Excessive wear on 

pads and end fittings 230 

c. Possible trouble — Tappet adjusting 

screws worn 231 

12C2. Push rods 231 

a. Possible trouble — Worn and loose end 

fittings 231 

D. Cam Followers and Lash Adjusters 

12D1. Roller type cam followers 231 

a. Possible trouble — Worn roller surface . . . 231 


b. Possible trouble — Worn cam follower 

body and guide 232 

c. Possible trouble — Worn roller needle 

bearings 232 

12D2. Mushroom type cam followers 232 

a. Possible trouble — Worn surfaces 232 

12D3. Hydraulic valve lifters or lash adjusters .... 232 
a. Possible trouble — Noisy operation of 

valve lifter 233 

Chapter 13. Piston and Connecting Rod Assembly 

A. Pistons 

1 3 A 1 . Trun k type pistons 235 

a. Possible trouble — Worn piston, exces- 

sive clearance 235 

b. Possible trouble — Cracked crown 238 

c. Possible trouble — Cracked lands 239 

d. Possible trouble — Piston skirt seizure . . 240 

e. Possible trouble — Crown and land 

dragging 241 

f. Possible trouble — Ring groove clearance 

insufficient 241 

g. Possible trouble — Clogged oil holes ... . 241 

h. Possible trouble — Piston pin bushings 

worn 242 

13A2. Crosshead type pistons 243 

a. Possible trouble — Worn and damaged 
piston skirt band on Hamilton-HOR 

pistons 243 

B. Piston Rings 

13B1. General 244 

a. Possible trouble — Worn compression 

rings 245 

b. Possible trouble — Worn oil rings 249 

c. Possible trouble — Sticking rings 250 

d. Possible trouble — Broken rings 251 

C. Piston Pins and Piston Pin Bearings 

13C1. General 252 

a. Possible trouble — Worn piston pins 252 

b. Possible trouble — Surface pitting and 

scoring of pins 253 

c. Possible trouble — Worn bushings 254 

d. Possible trouble — Worn needle bearings 255 

D. Connecting Rods 

13D1. General 255 

a. Possible trouble — Misaligned rod 255 

b. Possible trouble — Cracked rods 256 

c. Possible trouble — Defective bolts 257 

d. Possible trouble — Plugged oil passages. 258 
c. Possible trouble — Bore out-of-round — 258 

E. Cross he ads and Piston Rods 

13E1. Crossheads 259 

a. Possible trouble — Broken crosshead .... 261 

b. Possible trouble — Damaged crosshead 

pin and bushings 263 

c. Possible trouble — Wiped or pitted bab- 

bitt material on slipper 264 

13E2. Piston rods 265 

a. Possible trouble — Scored piston rod 265 

b. Possible trouble — Broken, shattered, 

bent, or seized piston rod 267 

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Chapter 14. Engine Shafts 

A. Crankshafts 

14A1. General 269 

a. Possible trouble — Scored journals 269 

b. Possible trouble — Broken or bent crank- 

shafts 271 

c. Possible trouble — Out-of-round journals 275 

B. Camshafts 

14B1. General 277 

a. Possible trouble — Damaged cams 277 

b. Possible trouble— Broken shafts 279 

c. Possible trouble — Failed camshaft bear- 

ings 280 

Chapter 15. Engine Journal Bearings 
A. General 

15A1. Introduction 281 

a. Possible trouble — Journal bearing 

failures 282 

Chaptbr 16. Anti-Friction Bearings 
A. Introduction 

16A1. General 295 

a. Possible trouble — Dirty bearing 297 

b. Possible trouble — Spallcd or pitted 

rollers or races 300 

C. Possible trouble — Dented (brinellcd) 

races 302 

d. Possible trouble — Failed separator 304 

e. Possible trouble — Races abraded on ex- 

ternal surfaces 305 

f. Possible trouble — Cracked race 305 

g. Possible trouble — Worn bearing 306 

Chapter 17. Auxiliary Drivb Mechanisms 

A. Introduction 

17A1. General 307 

B. Gears 

17B1. General 307 

a. Possible trouble — Gear failure 309 

C. Chains and Belts 

17C1. Chains 312 

a. Possible trouble — Worn or broken 

chains 312 

17C2. Belts 313 

a. Possible trouble — Excessive belt wear ... 313 

b. Possible trouble— Squeaking V-bclts 313 

Chaptbr 18. Clutches and Drive Gears 
A. Clutches 

18A1. Introduction 315 

18A2. Friction type clutches 315 

a. Possible trouble — Slippage 315 

b. Possible trouble— Wear 316 

c Possible trouble — Frozen clutch 316 

d. Possible trouble — Chattering clutch .... 316 

18A3. Dog type clutches 317 

a. Possible trouble — Difficulty in engaging 

clutch 317 

18A4. Falk Airflcx clutch 317 

a. Possible trouble — Broken airshaft tube. 317 

b. Possible trouble — Worn airshaft header 

and driver 318 

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c. Possible trouble — Oil clutch facings — 

slippage 318 

d. Possible trouble— Pressure contact 

maker 319 

e. Possible trouble — Clogged air filter 319 

f. Possible trouble — Misalignment of re- 

duction gear 319 

18A5. Fawick clutch and brake 321 

a. Possible trouble — Burned clutch and 

brake friction blocks 321 

18A6. Twin disk clutch 322 

a. Possible trouble — Worn clutch disks 322 

b. Possible trouble — Grease and oil on 

clutch surface 323 

18A7. Joe's gears 323 

a. Possible trouble — Slippage in the ahead 

position 323 

b. Possible trouble — Slippage in the astern 

position 323 

B. Drive Couplings 

18B1. Flange type solid coupling 324 

a. Possible trouble— Shafts misaligned or 

coupling bent 324 

18B2. Flexible couplings 325 

18B3. Hydraulic coupling, quick dump type 325 

a. Possible trouble — Dumping under load . 325 

C. Reduction and Reverse Gears 

18C1. General 326 

a. Possible trouble— Pitting 327 

b. Possible trouble — Foaming 328 

c. Possible trouble— Gear failure 328 

Chapter 19. Instruments 

A. Pressure 

19A1. Bourdon gage 329 

a. Possible trouble — Hole in Bourdon tube 

element 329 

b. Possible trouble — Broken cover glass .. . 330 

c. Possible trouble — Pointer fails to move. 330 

d. Possible trouble — Improper linkage ad- 

justment 330 

e. Possible trouble — Loose linkages and 

gears 331 

f. Possible trouble — Pointer docs not read 

zero for atmospheric pressure 332 

19A2. Manometers 332 

a. Possible trouble — Loss of pressure 333 

b. Possible trouble — Loss of liquid 333 

19A3. Engine indicators 333 

a. Possible trouble— Gummed indicator 

pistons 334 

b. Possible trouble — Electrical circuit 

failure 335 

c. Possible trouble — Gummed check valve. 337 

d. Possible trouble — Bourdon gage failure 338 

B. Temperature 

19B1. Liquid in glass thermometer 338 

a. Possible trouble — Broken cover glass . . . 338 

19B2. Expansion thermometer 338 

a. Possible trouble— Bourdon gage failures 339 

Origiral frcrn 


b. Possible trouble — Inaccurate tempera- 
ture readings 339 

19B3. Pyrometer 339 

a. Possible trouble — Pyrometer reads back- 

ward for one cylinder only 339 

b. Possible trouble — Pyrometer reads back- 

ward for every cylinder 340 

C. Possible trouble — Incorrect zero or open 

circuit pointer position 340 

d. Possible trouble — Incorrect temperature 

readings 340 

c. Possible trouble — Pointer fails to 

operate 342 

f. Possible trouble — Inaccurate tempera- 
ture readings 342 

19B4. Electrical resistance thermometer 342 

a. Possible trouble — Thermometer fails to 

record 342 

b. Possible trouble — Thermometer reads 

low 342 

C. Speed 

19C1. Mechanical centrifugal tachometers 343 

a. Possible trouble — Fluctuation of pointer 343 

19C2. Electrical tachometer 343 

a. Possible trouble — Pointer not at zero 

when engine is secured 344 

b. Possible trouble — Pointer reads astern 

with engine going ahead 344 

c. Possible trouble — Fluctuation of pointer 344 

d. Possible trouble — Tachometer reads low 344 

Digitized by GOOSES 




Ffr«r# Pmg, 

2-1. Scavenging systems 11 

2-2. Turbochargers 12 

2-3. Turbine wheel with damaged blade 14 

2-4. Roots type blowers 16 

2-5. Roots type blower for G.M. 3-268A engine showing 

helical rotors and timing gears 17 

2-6. Checking backlash of rotor gears 18 

2-7. Scored blower lobes 18 

2-8. Checking clearances of Roots type blower lobes ... 19 

2-9. Shaft oil seals 20 

2-10. Failed serrated shaft 21 

2-11. Hamilton-Whitfield blower 21 

2-12. Air intake manifold 22 

2-13. Schematic drawing of an oil separator 23 

2-14. Effect of a worn bearing on oil leakage 24 

2- 15. Flame primer as used on the G.M. -71 scries engine. 25 

3- 1. Cross section of manifold metal 27 

3-2. Formation of scale in water jacket 28 

3-3. Improper installation of wet type muffler 29 

3-4. Use of pipe bend to prevent backflow of water 29 

3-5. Use of three-way proportioning valve to regulate 

water flow to muffler 30 

3-6. Use of throttling valve to control flow of water to 

muffler 30 

3-7. Dry type muffler 31 

3-8. Force produced in exhaust piping by thermal 

expansion 32 

3-9. Use of flexible expansion joint to absorb thermal 

expansion 32 

3-10. Illustration of pressure drop in exhaust piping and 

muffler 33 

3-11. Types of bends used in exhaust lines 33 

3-12. Water trapped due to sagging of elbow 34 

3-13. Exhaust stack showing evidence of corrosion 34 

3- 14. Revision of stack design to eliminate corrosion 34 

4- 1. Schutte and Koerting gear pump 37 

4-2. Worn gear pump shafts 37 

4~3. Tuthill reversible fuel pump 38 

4-4. Packing clamps improperly tightened, cocked 39 

4-5. Cover plate of pump shown in Figure 4-4, showing 

uneven wear of bushing 39 

4-6. Vane type fuel oil pumps 40 

4-7. Worn and damaged seal on G.M. vane pump 40 

4-8. Bosch fuel supply pumps with hand prime feature. . 41 

4-9. Excello fuel transfer pump 41 

4-10. Schematic diagram of Bosch supply pumps 41 

4-11. Sectional views of Bosch type pumps : A — APF pump; 

B — 3-cylindcr APE pump 43 

Digitized by 


Figuri P*g* 

4-12. Pumping principle, one-plunger stroke 44 

4-13. Metering principle 44 

4-14. Types of plungers 44 

4-1 5. Plunger rotating mechanism 45 

4-16. Good and bad plungers 45 

4-17. APF pump sight window 48 

4-18. Typical Bosch spray nozzle 51 

4-19. Sectional views of nozzles 51 

4-20. Nozzle and nozzle holder 52 

4-21. American Bosch nozzle tester in operation 53 

4-22. Variations in nozzle holder connections and adjust- 
ments 54 

4-23. Throttling type pintle nozzle 56 

4-24. Good spray from throttling nozzles 56 

4-25. Spray patterns from standard pintle nozzles 56 

4-26. Types of General Motors injectors 59 

4-27. Injection and metering principle 60 

4-28. Injector test stand 60 

4-29. Sealing surfaces 62 

4-30. Type A Excello fuel injection pump 67 

4-31. Excello fuel pump drive unit, hydraulic unit, and 

safety filter 68 

4-32. Excello fuel injection nozzle 71 

4-33- Exploded view of nozzle tip 72 

4-34. Use of special tools to assemble and disassemble nozzle 73 

4-35. Cummins fuel system 74 

4-36. Cummins fuel injector 75 

4-37. Worn and scored distributor disk and cover 76 

4 38. Worn and eroded injector cup tip 79 

4-39. New injector cup tip 79 

4-40. Pressure regulating valve 79 

4-41. Atlas fuel system 80 

4-42. Spray valve and actuating mechanism 81 

4-43. Cutaway view of fuel oil pump 84 

4-44. Lapping the plunger and barrel 86 

4 45. Lapping the discharge vaive and seat 86 

4-46. Square lapping the relief valve seat 86 

4-47. Fuel injector 87 

4-48. Cutaway view of fuel injector 88 

4-49. Lapping the lower valve scat and stem 89 

4-50. Sectional view of fuel injection nozzle 90 

4-51 Recommended methods for elimination of pipe break- 
age at root of threads 91 

4-52. Duplex system (standard practice) 93 

4-53. Duplex fuel filter 93 

4-54. Plugging filter for washing 94 

4-55. Schematic drawing of a fuel system 95 

4-56. Strainer elements 96 

Original from 

Figwrt P"g* 

4- 57. Tank sampling device for diesel fuel 97 

5- 1. Elementary governor mechanisms 99 

5-2. G.M. mechanical governor 100 

5-3. Governor control mechanism 102 

5-4. Pierce mechanical governor 104 

5-5. Operating principle of hydraulic governor 108 

5-6. Marquette hydraulic governor 113 

5-7. Woodward type SI governor 114 

5- 8. Simple ovcrspecd trip mechanism 117 

6- 1 122 

6-2. 124 

6-3- Use of the centrifugal pump to clean heat exchangers 125 

6-4. Use of hand pumps and plungers to clean heat 

exchangers 125 

6-5. Repairing a strut tube leak. Both ends of tube require 

scaling 127 

6-6. Zinc electrode, before and after use 128 

6-7. Line valves 128 

6-8. Distortion of valve seat due to excess threads on pipe. 129 

6-9. Damaged gate valve, caused by throttling 130 

6-10. Tubing splice 133 

6-11. Simplex lube oil strainer 134 

6- 12. Michiana lube oil filter 135 

7- 1. Heat exchangers 138 

7-2. Harrison type cooler clement clogged with debris . . 139 

7-3. Attached centrifugal pump 142 

7-4. Worn sea- water pump clogged with seaweed 143 

7-5. Correct direction of rotation for unidirectional cen- 
trifugal pump 143 

7-6. Centrifugal pump with fluid sealed stuffing box .... 144 

7-7. Cracked kcyway in water pump impeller 145 

7-8. Disintegrated key and burred kcyway 146 

7-9. Location of wear rings on different types of centrif- 
ugal pumps 147 

7-10. Types of water pumps 148 

7-11. Failed neoprcne impellers 149 

7-12. Mistimed neoprcne impellers 149 

7—13- Water pump neoprcne gear failure through fatigue. . 150 

7-14. Synchronizing gears marked to avoid mistiming 150 

7-15. Neoprcne gear damaged by burning 150 

7-16. Lubricated plug valve 151 

7-17. Fulton-Sylphon automatic temperature regulator. . . 152 

7-18. Reference for adjustment instruction 153 

7-19. Installation of bulb 154 

7-20. Commonly used thermostats 155 

7-21. Sizing tools 159 

7-22. Steps in making a soldered joint 159 

7-23- Failure of piping at exposed thread 160 

7-24. Bends in copper tubing 160 

7-25. Typical sca-watcr strainer 161 

7-26. Clogged sea-water strainer 161 

7- 27. Dczincified (corroded) portions of sea-water strainer 161 

8- 1. Schematic diagram for checking insulation resistance 165 
8-2. Wiring diagram for checking resistance of the insu- 
lation, voltmeter method 165 

8-3. Checking belt tension 166 

8-4. Air pilot valve in Cooper-Bessemer type GSB-8 168 

8-5. Hamilton starting air distributor 169 

8- 6. Sectional view of air starting valve 169 

9- 1. Cutaway view of lead-acid cell 171 

9-2. Typical hard rubber battery case 172 

Figmrt P»g0 

9-3- Typical battery name plate 172 

9-4. Corroded and burned battery terminal 175 

9-5. Improperly tightened battery terminal and lug 176 

9-6. Checking belt tension 177 

9-7. Sanding a brush 177 

9-8. Testing an armature on the growler 178 

9-9. Preparing to test for polarity of field coils 178 

9-10. Wiring diagram of current and voltage regulator . . . 179 

9-11. Cleaning contact points 179 

9-12. Cutout relay adjustments 180 

9-13- Voltage regulator adjustments 180 

9^-14. Current regulator check 181 

9-15. Making a wire splice 183 

9-16. Diagrammatic sketch of connections for self-syn- 
chronous transmitters and indicators 184 

9-17. Wiring diagram, sclsyn remote control, a.c 184 

9-18. Schematic connection diagram of d.c. sclsyn system. 185 

9-19. Wiring diagram 185 

9- 20. A.C, D.C. split field motor 186 

10- 1. Cylinder block 187 

10-2. Crankcasc 187 

10-3. Cylinder block for Cooper-Bessemer GSB-8 188 

10-4. Engine base with main bearings and bearing caps in 

position, Cooper- Bessemer GSB-8 188 

10-5. Harmon Sav-A-Weld method for repairing cracks . . . 190 

10-6. Mctalock process for repairing cracks 190 

10-7. Use of cloth patches for cleaning passages 191 

10-8. Engine and reduction gear mounted on common 

sub-base 193 

10- 9. Welding in wandering sequence 194 

10-10. Generator set secured on flexible mounting 195 

10-11. Fundamentals of vibration isolator 195 

10-12. Spring type vibration isolator 196 

10-13- "Rubber sandwich" type flexible mounting 196 

10- 14. Vibration isolator-shock absorber 197 

11- 1. Schematic drawing of a cylinder assembly 199 

11-2. Cylinder head requiring no gasket 200 

11—3- Types of cylinder liners 200 

11 4. Wet liner with integral cooling passages 201 

11-5. Cracked cylinder liners 202 

11-6. Distortion of cylinder due to oversize seal ring 202 

11-7. Improper fillet preventing seating 202 

11-8. Scored cylinder liners 203 

11-9. Effect of scoring on seal between rings and liner 203 

11-10. Liner ports before and after stoning 204 

11-11. Liner ports before and after cleaning 205 

11-12. Measurements of cylinder wear 205 

11-13. Measuring a cylinder liner 206 

11-14. Common errors in taking inside micrometer readings 206 

11 — 15- Trace of moving end of micrometer calipers 207 

11-16. Combustion chambers 207 

11 17. Typical cylinder heads 208 

11-18. Cutaway view of cylinder head 209 

1 1-19. Water ferrule assembly 210 

11-20. Set-up to test for gas in cooling water 210 

11-21. Cracked cylinder head 210 

11-22. Cylinder head showing effect of leaking gasket 212 

11-23. Cylinder head studs in place 213 

11-24. Cylinder head stud designs 213 

11-25. Failure at root of thread 214 

11-26. Failure in shank 214 

Digitized by tjOOQlC 

Origiral from 

Figft Pag* 

11-27. Effect of uneven stud tightening 214 

11-28. Use of special stud wrench 215 

11-29. Use of two nuts to drive stud 215 

11-30. Minimum effective thread length for stud 216 

11-31. Two methods for removing a broken stud 216 

11-32. Procedure for extracting a broken stud 217 

11-33. Use of pilot hole to aid in drilling of stud 217 

11-34. Principle of a gasket 218 

11-35. Types of cylinder head gaskets 218 

11-36. Effect of uneven tightening on a gasket 219 

11- 37. Proper order for tightening cylinder head studs 219 

12- 1. Exhaust valves 222 

12-2. Excessively lapped valves 224 

12-3. Exhaust valve springs 225 

12-4. Poppet valve assembly 226 

12-5. Valve stem cap 226 

12-6. Exhaust valves, G.M. 8-268A 226 

12-7. Damaged and undamaged cylinder heads 227 

12-8. Damaged valves from cylinder head shown in Figure 

12-7A. Broken valve that caused damage is not 

shown 228 

12-9. Supercharge valves in HOR engine 229 

12-10. Roller type cam followers 231 

12- 11. Lash adjuster 233 

13- 1. Typical trunk type piston 236 

13-2. Cylinder lubricators, Hamilton diesel 237 

13-3- Severe scoring of cylinder walls caused by piston 

seizure 238 

13-4. Piston scored by seizure. Note broken rings 238 

13-5. Piston measurements 238 

13-6. Piston skirt seizure — galling 241 

13-7. Piston ruined by clogged oil holes and seizure 242 

13-8. Location of joint in piston pin bushings for piston 

and connecting rod 243 

13-9. Hamilton double-acting crosshead type piston and 

piston rod 243 

13-10. Cylinder lube oil check valve 244 

13-11. General types of piston rings 245 

13-12. Common types of piston ring gaps 245 

13-13. Piston ring nomenclature 245 

13-14. Removing and replacing piston rings with piston 

ring tool 247 

1 3-1 5. Using metal strips to remove piston rings 247 

13-16. Shoulder in ring groove due to wear 248 

13-17. Level ring in bore with inverted piston 248 

13-18. Installing piston in cylinder bore with funnel type 

piston ring compressor 248 

13-19. Using wire to install piston rings 249 

13-20. Checking for stuck rings 249 

13-21. Examples of piston pin bearings 252 

13-22. Piston pin measurements 253 

1 3-23- Reaming tools 253 

13-24. Measuring the piston pin and piston pin bushing for 

wear 254 

13-25. Common types of connecting rods 256 

13-26. Critical area of a connecting rod 256 

13-27. Connecting rod bolts 257 

13-28. Incorrect and correct installation of cotter pins 257 

13-29. Measuring the bore of a connecting rod for out-of- 

roundncss 258 

13-30. Single-acting engine 259 

Digitized by (^QO 

Figurt P*H 

1 3-31 • Double-acting engine 260 

13-32. Crosshead and connecting rod assembly 260 

13-33. Exploded view of Hamilton HOR assembly 261 

13-34. Crosshead guide and crosshead guide gibs 261 

13-35- Spherical nut 261 

13-36. Crosshead cover nut 262 

13-37. Piston cooling linkage 263 

13-38. Checking alignment of connecting rods 265 

13-39. Stuffing box 266 

13- 40. Division cover 266 

14- 1. Diesel engine crankshaft 269 

14-2. Crankshaft oil passages 270 

14-3. Crankshaft with hollow crank pins 270 

14-4. Cracked journal 272 

14-5. Broken crankshaft 272 

14-6. Cracked crank web 273 

14-7. Fatigue failure resulting from torsional vibration 274 

14-8. Strain gage installed between crank webs 274 

14-9- Crankshaft bridge gage 275 

14-10. Measurement of crank-pin diameter. 275 

14-11. Diesel engine camshaft 276 

14-12. Built-up camshaft 276 

14-13. Individual cam 276 

14-14. Built-up camshaft 277 

14-15. Camshaft with adjustable fuel pump cams 277 

14-16. Camshaft showing lubrication passageways 277 

14-17. Cracked cam 278 

14-18. Camshaft key drift 278 

14-19. Installing a camshaft 279 

14- 20. Broken camshaft 280 

15- 1. Fatigue failure (magnified) 282 

15-2. Fatigue failure 282 

15-3. Failure due to corrosion 283 

15-4. Corroded bearing 283 

15-5. Corrosion 284 

15-6. Corroded copper-lead bearing 284 

15-7. Bearing failure due to inadequate bond 285 

15-8. Bond between tin-base babbitt and bronze shell 285 

15-9. Embedded foreign particles in a Tri-mctal bearing. . 285 

15-10. Defective bond between bronze and steel of a Tri- 

metal bearing 286 

15-11. Failure due to extrusion of bronze back into the 

connecting rod oil groove 286 

15-12. Bearing failure caused by faulty installation 287 

15-13. Proper and improper fitting locking lip 288 

15-14. Failed bearing 289 

15-15. Bearing with ability to carry the load after part of the 

bearing area has failed 290 

15-16. Pitted bearing surface 290 

15-17- Wiped bearing 290 

15-18. Overheated bearing 291 

15-19. Scratched bearing 291 

15-20. Proper care of bearings 291 

15-21. Use of torque wrench to tighten connecting rod bolt 

nuts 291 

15-22. Gage used to measure stretch in connecting rod bolts . 292 

15-23. Measuring stretch in connecting rod bolts 292 

15-24. Bearing micrometer 293 

15- 25. Measuring bearing thickness 293 

16- 1. Variations in bearing design 295 

16-2. Ball and roller bearings 296 

Original from 

Figurt P*gt 

16-3- Connecting rod needle bearing 297 

16-4. Benches for bearing work . 297 

16-5- Anti-friction bearing scaling devices 298 

16-6. Thimble for mounting flange type seal 299 

16-7. Wire basket for cleaning bearings 299 

16-8. Cleaning bearing with compressed air 300 

16-9. Spalled roller and races 301 

16-10. Spalling due to loose adjustment 301 

16-11. Spalling due to misalignment 302 

16-12. Brinellcd races 302 

16-13- How to ruin a bearing 302 

16-14. Correct methods of bearing removal 303 

16-15- Split ring for removal of inaccessible bearings 304 

16-16. Failure of separator 304 

16-17. Abrasion of external surface of inner race 305 

16- 18. Bearing with cracked inner race 306 

17- 1. Timing gear train 307 

17-2. Camshaft timing gear train 307 

17-3. Drive chain assembly 308 

17-4. Split crankshaft gear 309 

17-5. Pitted metal gear 310 

17-6. Checking backlash of rotor gears 310 

17-7. Worn fibre gear 310 

17-8. Chipped gear tooth 311 

17-9. Broken gear tooth 311 

17-10. Defective gear determination .• 311 

17-11. Engine gear set 312 

17- 12. Chain connection assembly 313 

18- 1. Falk Airflcx clutch 317 

18-2. Brazing sctscrews into air tubes 318 

18— 3- Checking angular and parallel alignment of pro- 
peller shafts 320 

18-4. Cross section of Fa wick reverse gear as used on G.M. 

278 engine 321 

Figurt Psg$ 

18-5. Damaged twin-disk clutch disk 322 

18-6. Joe's reverse gear 323 

18-7. Flange type solid coupling 324 

18-8. Flange type solid coupling with shoulder and recess . . 325 

18-9. Checking alignment with dial gage 325 

1810. Hydraulic coupling, quick dump type 326 

18-11. Farrell-Birmingham single reduction gear 326 

18-12. Location of pitch line 326 

18-13. Corroded tooth 327 

18-14. Pitting due to profile error 327 

18-15. Pitting due to improper lead angle 327 

18- 16. Pitting due to misalignment 327 

19- 1. Bourdon gage 329 

19-2. Adjustment of Bourdon mechanism 330 

19-3. Dead weight tester 331 

19-4. U-tube manometer, open type 332 

19-5. Premax indicator, model YBC 333 

19-6. Bacharach model YRF engine pressure indicator 335 

19-7. Poor indicator connection 335 

19-8. Good indicator connection 336 

19-9. Kienc indicator 336 

1910. Kienc indicator pressure chamber, internal view 336 

1911. Kienc indicator installed on engine 337 

19-12. Reconditioning a valve seat (A) and valve (B) 337 

19-13- Thermometer 338 

1914. Expansion thermometer 338 

19-15. Pyrometer installation 339 

19-16. Sectional view of a thermocouple 339 

19-17. Comparison of used and unused thermocouple units. 341 

19-18. Removing thermocouple unit from engine 341 

19-19. Portable pyrometer 342 

19-20. Duplex resistance thermometers 342 

19-21. Electrical tachometer 343 

Digitized by GOOSES 

Origiral from 




1 A1 . Recognizing and locating troubles. A com- 
paratively minor engine trouble, if not recognized and 
remedied in its early stages, may easily develop into a 
major breakdown. Furthermore, this complete failure 
may occur at a critical moment, imperiling both ship 
and crew. Consequently, every diesel operator must 
be a trouble shooter. 

The successful trouble shooter must meet the fol- 
lowing qualifications: 

1. He must be able to recognize symptoms of 
trouble when he sees, hears, smells, or feels them. 

2. Having decided that something is wrong with 
the engine, he must be able to determine expeditiously 
what repairs may be necessary. 

It must be remembered that the engine frequently 
continues to operate even when a serious casualty is 
imminent. However, symptoms of the impending 
trouble are almost always present. 

One of the best methods for detecting trouble is to 
read regularly and record in the log, engine instrument 
indications. Should the instrument readings vary 
markedly from those specified in the engine instruc- 
tion manual, the operator knows that the engine is 
not operating properly and that adjustment must be 
made. He must, therefore, be familiar with the speci- 
fications given in the engine instruction manual 
regarding proper temperatures, pressures, speeds, and 
so forth. He should also try to visualize the probable 
effect on the engine of variations from these specified 
values. The exact significance of pressure and temper- 
ature readings depends largely on the location of the 
instruments in the system. For this reason, the opera- 
tor should be familiar with their location. 

Another good method for the recognition of trouble 
is to be attentive to unusual engine noises that may 


Digitized by 

Go gle 

occur during operation. Although the diesel engine is 
inherently noisy, an observant operator is quick to 
notice changes in the normal operating sounds. 
Whenever an unusual noise occurs, it is an indication 
that something within the engine is not normal. It 
is then the responsibility of the operator to determine 
the cause of the noise. 

The trouble shooter must also make periodic inspec- 
tions to discover failure of visible parts, presence of 
smoke, or leakage of lube oil, fuel oil, or water. 
Leakage is observed most readily when the exterior of 
the deck, engine, and piping are kept spotlessly clean. 
Hence, wiping down the engine room not only makes 
that space shipshape and more livable, but also 
facilitates trouble shooting. 

As soon as a symptom of trouble is recognized, the 
operator must automatically do several things. He 
must decide immediately whether it is necessary to 
secure the engine. In most cases where the engine 
becomes unnecessarily noisy or engine instrument in- 
dications become extreme, it is necessary to secure the 
engine. Continued operation under such conditions 
frequently leads to extensive damage. However, it 
may be advisable to repair minor damage, such as a 
leak in piping, without securing the engine. The 
severity of the trouble and the immediate requirement of the 
ship for the engine determine whether an engine is to be se- 
cured or allowed to continue operating. 

Once the engine is secured, the operator must begin 
a search for the cause of the trouble. It is evident that 
an endless task confronts the operator who attempts to 
inspect each individual engine part every time a 
trouble occurs. Therefore, some systematic and logical 
method of inspection must be followed if the cause of 
the trouble is to be localized quickly. The best method 
is to isolate the trouble by identifying it with one of 
the engine's systems, for example, the air intake sys- 




tern, the lubricating system, or the fuel system. The 
next step is to trace out that system until the failure is 
uncovered. This usually is possible because troubles 
generally originate in only one system. However, it is 
to be remembered that the troubles occurring in one 
system may cause damage in other systems. If the 
derangement involves more than one engine system, 
each system must be traced through separately and 
each irregularity corrected. Obviously, the operator 
must know the systems and the purpose of each piece 
of equipment in the system before he can satisfactorily 
locate and remedy troubles. This knowledge is best 
attained by a thorough study of the engine instruction 

The trouble shooter can save considerable time by 
analyzing the symptoms of the trouble and deciding, 
before starting to work on the engine, which compo- 
nents of the system under consideration can be sus- 
pected most logically of having caused the observed 
symptoms. Of these components, those most readily 
checked should be examined first. 

In instances where the symptoms definitely indicate 
which engine system is at fault, but give no clue as to 
which piece of equipment in the system may be respon- 
sible, it is advisable to start at the beginning of the 
system and trace completely through until the source 
of trouble is located. 

In Chapter 1, the most common engine symptoms 
are listed, with the possible troubles responsible for 
these symptoms. The information is necessarily gen- 
eral and, at best, will serve only as a pattern for pros- 
pective trouble shooters. Constant reference should 
be made to the remainder of the book for a complete 
discussion of the most common diesel engine troubles, 
their causes, how to prevent them, and the repairs that 
are necessary. 

Although experience is a great asset to the trouble 
shooter, any operator who conscientiously studies his 
engine, uses his common sense, and exercises his latent 
detecting ability, will soon be able to diagnose and 
correct engine troubles quickly and accurately. 


787. Engine will not crank but can be barred over* 

a. Air starting system — Possible troubles: 

1. Starting air supply is depleted due to: 

(a) Failure to refill the storage tanks after 

the last start. 

(b) Leaks in the air piping or valves. 

2. Valve in the air line is not open. 

3. Jacking gear interlock is engaged. 

Digitized by GOuQIC 

4. Improper functioning of the air starting 


5. Improper functioning of the cylinder air start 


b. Electrical system — Possible troubles: 

1. Dead battery. 

2. Loose cables. 

3. Faulty starter switch due to: 

(a) Improper functioning of the solenoid. 

(b) Improper functioning of the push 


4. Faulty starting motor due to: 

(a) Dirty commutator. 

(b) Burned brushes. 

(c) Damaged motor field or armature. 

5. Jammed starter gear. 

702. Engine cannot be cranked and cannot be barred 

a. Possible troubles: 

1. Jacking gear not engaged properly. 

2. Seized piston. 

3. Water or other obstructions in the cylinder. 

4. Bearings fitted too tightly. 

1B3. Engine cranks but fails to start. 

a. Possible troubles: 

1. Insufficient cranking speed due to: 

(a) Low starting air pressure, weak bat- 

tery, or poor battery connections. 

(b) Lubricating oil viscosity too great. 

(c) Worn rings. 

(d) Leaky valves. 

2. Fuel contamination due to: 

(a) Air in the fuel. 

(b) Water in the fuel. 

3. Fuel throttle in OFF position. 

4. Insufficient fuel supply due to: * 

(a) Insufficient fuel supply in the day tank. 
(h) Clogged fuel filters or strainers. 

(c) Inlet valve closed in the fuel piping. 

(d) Leaks in the fuel piping. 

(e) Fuel system not primed. 

(f) Inoperative fuel transfer pump. 

(g) Inoperative high-pressure injection 


5. Unsuitable fuel oil. 

6. Improper timing of the fuel system. 

7. Insufficient compression in the cylinders due 


(a) Leaky cylinder head gasket. 

(b) Leaky valves. 

Qrigiral from 


(c) Worn rings. 

(d) Cylinder indicator valves open. 

8. Overspeed trip accidentally tripped. (Some 

engines are equipped with trips that secure 
the engine, while others are equipped with 
an overspeed governor that merely returns 
the engine to its rated speed when the 
engine speed becomes excessive.) 

9. Engine governor inoperative due to: 

(a) Low oil level (if the governor is hy- 


(b) Binding of the control linkages. 
10. Cold starting device inoperative. 


TO. Engine stalls frequently. 

a. Possible troubles: 

1. Fuel system air bound. 

2. Incorrect governor operation due to: 

(a) Dirty governor or linkage. 

(b) Improper adjustment of the governor 

or linkage. 

3. Clogged fuel filters. 

4. One or more cylinders missing. 

5. Unsatisfactory operation of the fuel injection 

equipment due to: 

(a) Pump or nozzles sticking. 

(b) Worn injectors. 

(c) Defective pump. 

6. Cooling water temperature too low. 

7. Load applied too suddenly at low speeds. 

8. Improper timing of the valves. 

1C2. Engine stops suddenly. 

a. Possible troubles: 

1. Fuel contamination due to: 

(a) Air in the fuel. 

(b) Water in the fuel. 

2. Insufficient fuel supply due to: 

(a) Empty fuel tank. 

(b) Clogged filters and strainers. 

(c) Inoperative fuel supply pump. 

(d) Inoperative fuel injection pump. 

(e) Clogged fuel lines. 

3. Overspeed trip stops the engine due to im- 

proper functioning of the engine governor 
or trip. 

4. Obstructed exhaust manifold. 

5. Insufficient scavenging air due to: 

(a) Blower failure (seized blower rotors, 
or broken drive shaft). 

Digitized by 

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(b) Clogged air silencer or air filter. 

6. Piston seizure. 

7. Derangement of the gear train or chain drive. 

1C3. Engine overspeeds. 

a. Possible troubles: 

1. Improper functioning of the governor mech- 


2. Fuel pump control linkage binds. 

3. Tachometer inaccurate and reads low, caus- 

ing the operator to attempt to bring the 
engine speed up to correspond to the rated 
speed as registered on the tachometer. 

1C4. Engine will not carry load (loss of power). 

a. Possible troubles: 

1. Low compression pressure due to: 

(a) Leaky cylinder head gasket. 

(b) Leaky valves. 

(c) Worn rings. 

(d) Crack in the cylinder head or block. 

(e) Worn pistons and/or liners. 

2. Insufficient fuel due to: 

(a) Dirty filters. 

(b) Leaky fuel lines. 

(c) Fuel supply or transfer pump parts 

excessively worn. 

(d) Fuel injection pump parts excessively 


3. Incorrect timing of the fuel injection system. 

4. Clogged nozzles or spray tips. 

5. Obstructions in the exhaust passages or 


6. Fuel control racks not properly positioned. 

7. Improper governor action. 

8. One or more cylinders misfiring due to: 

(a) Faulty injection equipment. 

9. Insufficient supply of air due to: 

(a) Clogged air intake ports. 

(b) Clogged air cleaner or silencer. 

10. Misalignment between the engine and pro- 
peller shaft. 

TC5. Engine will not shut off. 

a. Possible troubles: 

1. Improper adjustment or misalignment of the 

fuel control linkage. 

2. Stuck injector racks. 

3. Fuel oil leakage from the injectors. 

4. Lube oil leakages to the blower and air box. 




1C6. Engine misfires or fires erratically. 

a. Possible troubles: 

1. Air in the fuel. 

2. Dirty fuel niters. 

3. Water in the fuel. 

4. Faulty nozzles. 

5. High-pressure injection pump troubles. 

6. Plugged air cleaner or silencer. 

7. Sticking or leaking cylinder valves. 

8. Worn pistons or liners. 

1C7. One engine cylinder misfires regularly. 

a. Possible troubles: 

1. Injection pump casualty to that particular 

cylinder due to: 

(a) Stuck plunger. 

(b) Fuel pump cutout mechanism engaged 

(some fuel pumps are equipped with a 
mechanism to cut out fuel injection 
to the cylinder in order that com- 
pression pressures may be measured). 

2. Faulty nozzle. 

3. Cylinder intake or exhaust valve sticking. 

4. Loss of compression in that particular 

cylinder due to: 

(a) Leaky cylinder head gasket. 

(b) Leaky valves. 

(c) Worn rings. 

(d) Crack in the cylinder head or block. 

(e) Worn pistons and or liners. 

1C8. Cylinder safety valves pop frequently during 
engine operation. 

a. Possible troubles: 

1. Excessive amount of fuel injected into 

cylinder due to: 

(a) Improper functioning of the high 

pressure injection pump. 

(b) Leaky nozzle or spray valve. 

(c) Loose fuel cam (if the cam is ad- 


(d) Fuel pressure in the common rail too 

high (if that is the system used). 

2. Insufficient tension on the safety valve spring. 

3. Excessive amount of lube oil in the cylinder. 

4. Broken supercharge valve (if an HOR engine). 

5. Clogged or partially obstructed exhaust 


7C9. Engine will not reach rated speed. 

a. Possible troubles: 

1 . Improper adjustment of the fuel control rack. 

2. Improper adjustment of the governor or 


3. Engine overloaded. 

4. Faulty injection equipment. 

TOO. Engine hunts (speed varies at constant throttle 

a. Possible troubles: 

1. Improper functioning of the engine governor 

due to: 

(a) Sticky linkage. 

(b) Dirty governor. 

(c) Improper adjustment of the governor. 

2. Load fluctuating too unevenly for the gover- 

nor to maintain absolutely constant speed. 


1D1. Pounding. 

a. Possible troubles: 

1. Loose or excessively worn main and connect- 

ing rod bearings. 

2. Worn piston pin and piston pin bushing or 


3. Worn crosshead pin or crosshead pin bush- 

ings (double acting engine). 

4. Loose counterweights on the crankshaft. 

5. Worn camshaft bearings and auxiliary shaft 


6. Worn rocker arm bushings. 

7. Broken gears. 

8. Failed auxiliary drive gears. 

1D2. Knocking. 

a. Possible troubles: 

1. Detonation, or fuel knock, due to: 

(a) Engine not warmed up. 

(b) Early injector timing. 

(c) Leaky injection spray valves. 

1D3. Metallic clicking. 

a. Possible troubles: 

1. Improper functioning of the valve and valve 

operating mechanism due to: 

(a) Loose valve stem and guide. 

(b) Insufficient or excessive valve tappet 


(c) Loose cam follower or guide. 

(d) Valves stuck open. 

(e) Broken valve springs. 

2. Broken gear teeth in timing gear train. 

Digitized by tjOOQlC 

Origiral from 


IDA. Rattling. 

a. Possible troubles: 

1. Improper functioning of the vibration 


2. Loose engine parts (bolts not tightened). 

3. Gear pump operating without prime. 

4. Antifriction bearing failure. 

Note: Detonation in some small high-speed engines may 
exhibit itself as a rattle rather than a knock. 


Note: The system should be studied carefully as the 
location of the pressure gage influences the sig- 
nificance of a pressure reading. 

1E1. Low lube oil pressure. 

a. Possible troubles: 

1. Inoperative or inaccurate oil pressure gage. 

2. Oil gage line plugged. 

3. Clogged filters and strainers and/or a sticking 

pressure relief valve (bypass around filter) 
stuck closed. 

4. Clogged lube oil cooler. 

5. Pressure relief valve (bypass) around the lube 

oil pump stuck open. 

6. Too low a setting on the pressure regulating 


7. Worn or inoperative lube oil pump. 

8. Worn connecting rod, main and camshaft 


9. Worn valve rocker arm bushings. 

10. Low oil level in the crankcase or storage 


11. Lube oil diluted with fuel oil. 

12. Leaks in the lube oil piping. 

13. The use of oil with a viscosity lower than 


1 E2. High lube oil pressure. 

a. Possible troubles: 

1. Inaccurate pressure gage. 

2. Improper functioning of the pressure relief 

valve due to: 

(a) Stuck valve. 

(b) Spring setting too high. 

3. Unsuitable lubricating oil (viscosity too 


1E3. Low fuel oil pressure (in low-pressure fuel supply 

a. Possible troubles: 

Digitizes by GCX 'fllC 

1. Inoperative or inaccurate fuel oil pressure 


2. Fuel oil gage line plugged. 

3. Clogged filters or strainers. 

4. Inoperative or worn fuel oil transfer pump. 

5. Insufficient fuel supply in the day tank. 

6. Leaks in the fuel oil piping. 

7. Clogged fuel oil lines upstream from the 

pressure gage. 

1EA. Low cooling water pressure (fresh). 

a. Possible troubles: 

1. Inoperative or inaccurate water pressure 

2. Clogged fresh water cooler. 

3. Circulating water system air bound. 

4. Water pressure gage line plugged. 

5. Insufficient makeup water to compensate for 

evaporation losses. 

1E5. Low cooling water pressure (salt). 

a. Possible troubles: 

1. Salt water system air bound. 

2. Clogged cooler. 

3. Inoperative or inaccurate water pressure gage. 

4. Gage line clogged. 

5. Clogged inlet strainer. 

1E6. High cooling water pressure (salt). 

a. Possible troubles: 

1. Sea water side of the cooler clogged. 

2. Inoperative pressure relief valve around the 

gear pump (if this type of pump is cm- 
ployed) due to: 

(a) Stuck valve. 

(b) Spring setting too high. 

3. Discharge valve partially closed (this valve 

is downstream of the gage). 

1E7. Low compression pressure. 

a. Possible troubles: 

1. Worn, broken, or stuck rings. 

2. Worn pistons or liners. 

3. Leaking cylinder head gasket. 

4. Inaccurate pressure measuring device. 

5. Leaking cylinder head valves. 

6. Incorrect timing of the exhaust and intake 


7. Crack in the cylinder head or block. 

8. Insufficient air supply due to: 

(a) Inoperative blower. 

(b) Clogged scavenging air ports. 

(c) Clogged air filters. 

Origiral frcrn 


1 £8. Low firing pressure. 

a. Possible troubles: 

1. Inaccurate pressure measuring device. 

2. Unsuitable fuel oil. 

3. Improper timing of the injectors (especially, 

late timing). 

4. Low compression pressure. 

5. Insufficient delivery of fuel to develop the 

required power due to: 

(a) Worn injection pump parts. 

(b) Clogged nozzles. 

1E9. High firing pressure, 

a. Possible troubles: 

1. Detonation due to: 

(a) Poor grade of fuel. 

(b) Cold engine. 

(c) Early injection timing. 

(d) Leaky nozzles. 

2. Engine overloaded. 

3. Maximum fuel setting incorrect. 

1E10. Low scavenging air receiver pressure (super- 
charged engine). 

a. Possible troubles: 

1. Inaccurate or inoperative pressure gage. 

2. Clogged gage line. 

3. Faulty operating blower or supercharger. 

4. Clogged air silencer, screen or air filter. 

1E11. High exhaust back pressure. 

a. Possible troubles: 

1. Improper functioning of the wet or dry type 


2. Restricted muffler. 


Note: Study the systems carefully, as the locations of 
the temperature measuring devices influence the 
significance of divergent readings. 

7 FT. Low lube oil temperature. 

a. Possible troubles: 

1. Inaccurate temperature gage. 

2. Excessive amount of cooling water entering 

lube oil cooler. 

3. Improper functioning of the temperature 

regulating device. 

4. Insufficient heating of the oil in the tank 

(cold weather). 

5. Engine not thoroughly warmed up. 

Digitized by 

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1F2. High lube oil temperature. 

a. Possible troubles: 

1. Insufficient circulation of the oil due to: 

(a) Worn lube oil pump. 

(b) Low lube oil level in the supply tank. 

(c) Faulty operating pressure relief or pres- 

sure regulating valve. 

(d) Clogged lube oil lines. 

2. Inaccurate temperature gage. 

3. Insufficient cooling due to: 

(a) Clogged oil cooler. 

(b) Low sea water or fresh water pressure. 

(c) Fresh water or salt water system air 


(d) Automatic lubricating oil temperature 

regulating valve stuck or not prop- 
erly adjusted. 

(e) Manual lubricating oil temperature 

regulating valve not properly ad- 

(f) High fresh water temperature. 

4. Engine overloaded. 

5. Worn main, connecting rod, piston pin, and 

camshaft bearings. 

1F3. Low cooling water temperature (fresh). 

a. Possible troubles: 

1. Inaccurate or inoperative temperature gage. 

2. Insufficient engine load. 

3. Thermostats not functioning properly. 

1F4. High cooling water temperature (fresh). 

a. Possible troubles: 

1. Insufficient supply of fresh water due to: 

(a) Low level in the expansion tank. 

(b) Inoperative or worn fresh water pump. 

(c) Improper setting on the temperature 


(d) Fresh water system air bound. 

(e) Improper action of the thermostats. 

2. Insufficient supply of salt water through the 

fresh water cooler due to: 

(a) Clogged cooler. 

(b) Inoperative or worn salt water pump. 

(c) Salt water system air bound. 

(d) Clogged inlet strainer or screen. 

3. Faulty temperature gage. 

4. Overloaded engine. 

5. Blown cylinder head gasket. 

Qrigiral from 


1F5. Low cylinder exhaust temperature. 

a. Possible troubles: 

1. Light mechanical or electrical load. 

2. Insufficient supply of fuel. 

3. Injection advanced too much. 

4. Inaccurate temperature measuring device. 

1F6. High exhaust temperature in one cylinder. 

a. Possible troubles: 

1. Inaccurate temperature measuring device. 

2. Fuel pump rack stuck in FULL fuel position. 

3. Late injection timing. 

4. Fuel pump injecting an abnormal amount of 

fuel to the cylinder. 

5. Broken supercharge valve (HOR engine). 

6. High exhaust back pressure. 

7. Cooling water flow stopped or partially 

restricted to the cylinder. 


1G1. Low firing pressure and low exhaust tern* 

a. Possible trouble: 

1. Insufficient fuel supply caused by improper 
positioning of the fuel rack. 

7G2. Low firing pressure and high exhaust tempera- 

a. Possible troubles: 

1. Late injection. 

2. Insufficient clearance of the exhaust valve or 


3. Leaky fuel nozzle. 

7G3. High firing pressure and low exhaust 

a. Possible trouble: 

1. Early injection. 

1G4. High firing pressure and high exhaust tem- 

a. Possible trouble: 

1. Excessive amount of fuel delivered. Increase 
of improper positioning of the fuel control 

Digitized by GCK HjlC 

1GS. Low compression pressure and low exhaust 

a. Possible troubles: 

1. Cylinder head gasket too thick. 

2. Shim between connecting rod and crankpin 

box too thin (if present). 

3. Excessive main and connecting rod bearing 


1G6. Low compression pressure and high exhaust 

a. Possible troubles: 

1. Leaking valves. 

2. Improper exhaust valve clearance. 

3. Worn or stuck piston rings. 

4. Worn cylinder lining. 

1G7. High compression pressure and low exhaust 

a. Possible trouble: 

1. Cylinder head gasket too thin. 

7G8. High compression pressure and high exhaust 

a. Possible trouble: 

1. Engine overloaded. 


1H1. Idling speed not normal. 

a. Possible troubles: 

1. Improper idle adjustment of the governor. 

2. Faulty tachometer due to: 

(a) Insufficient magnetic field (electrical 


(b) Improper zero setting. 

(c) Binding or excessive friction in the 

tachometer cable will cause erratic 

1H2. Maximum speed not normal. 

a. Possible troubles: 

1. Engine overloaded. 

2. Faulty tachometer due to: 

(a) Insufficient magnetic field (electrical 


(b) Improper zero setting. 

(c) Binding or excessive friction in the 

tachometer cable will cause erratic 

3. Maximum speed adjustment of the governor 


Origiral frcrn 



111. Black exhaust smoke. 

a. Possible troubles: 

1. Engine overloaded. 

2. Clogged air cleaner. 

3. Insufficient valve tappet clearance, holding 

valve open continuously. 

4. Improper timing and metering of fuel. 

5. Clogged fuel filters. 

6. Stuck piston rings. 

7. Burned or cracked nozzle or spray tip. 

8. Insufficient opening pressure of fuel nozzle 

causing fuel drip. 

9. Uneven cylinder load balance. 

10. Unsuitable fuel or lube oil. 

11. Low compression. 

112. Bluish-white exhaust smoke. 

a. Possible troubles: 

1. Worn piston or piston rings. 

2. Excessive cylinder lubrication (double acting 


3. Leaky stuffing box cooling oil (double 

acting engine). 

4. Cylinder misfiring. 

7/3. Smoke arising from crankcase. 

a. Possible troubles: 

1. Crankcase explosion. 

2. Seized main or connecting rod bearings. 

3. Blow-by caused by: 

(a) Worn liners, rings, pistons. 

4. Stuck piston rings. 

5. High lube oil temperature due to: 

(a) Insufficient circulation of oil caused by: 

(1) Worn lube oil pump. 

(2) Low oil level in the supply tank. 

(3) Clogged lines. 

(b) Faulty pressure relief or regulating 


(c) Insufficient cooling caused by: 

(1) Clogged oil cooler. 

(2) Low sea- or fresh-water pressure. 

(d) Engine overloaded. 

114. Smoke arising from cylinder head. 

a. Possible troubles: 

1. Leaky cylinder head gasket. 

2. Leaky fuel injector gasket, fuel nozzle gasket, 

or fuel spray valve gasket. 

3. Cooling water not circulating. 

Digitized by 


4. Crack in cylinder head. 

5. Worn valve guides. 

7/5. Smoke arising from engine auxiliary equipment 
(blower, pumps, etc.). 

a. Possible troubles: 

1. Wiped bearings. 

2. Blower lobes in contact with blower housing. 


1)1. Excessive lube oil consumption. 

a. Possible troubles: 

1. Oil leaks in the lube oil piping and lube oil 


2. Incorrect grade of lube oil. 

3. Stuck or worn piston rings. 

4. Worn pistons or cylinder liners. 

5. Incorrect piston ring gap. 

6. Operating with too high a lube oil tem- 


7. Worn or defective oil seals (crankshaft, 

blower, etc.). 

8. Stuck valves. 

1J2. Excessive fresh water consumption. 

a. Possible troubles: 

1. Engine overloaded. 

2. Leaks in the water piping and in the water 


3. Operation with excessive fresh water tem- 


1J3. Excessive fuel oil consumption. 

a. Possible troubles: 

1. Inefficient combustion due to: 

(a) Nozzle difficulties. 

(b) Fuel pump or injector troubles. 

2. Leaks in the fuel oil piping. 

3. Fuel oil dilution in the lube oil due to: 

(a) Worn rings. 

(b) Worn liners. 

(c) Leaks. 

4. Overloaded engine condition. 


1K1. Fuel oil in the lube oil. 

a. Possible troubles: 

1. Worn or stuck rings. 

2. Worn cylinder liners or pistons. 




3. Fuel leaks. 

4. Blown cylinder head gasket. 
5- Leaky nozzles, injectors. 

6. Dilution will occur with continuous opera- 

tion at low speeds and idling. 

7. Improper performance o/ the drainage system 

in the neighborhood of the fuel injection 

1K2. Water in the lube oil. 

a. Possible troubles: 

1. Water in the combustion chamber due to: 

(a) Leaky cylinder liner. 

(b) Leaky head. 

(c) Leaky gasket. 

2. Condensation. 

3. Faulty operation of the centrifuge or failure 

to use the centrifuge with sufficient 

4. Leak in oil cooler. 

1K3. Oil or grease in the water. 

a. Possible troubles: 

1. Leaky oil cooler due to: 

(a) Leaky tubes. 

(b) Worn or damaged gaskets. 

2. Overlubrication of the water pump bearings. 

1K4. Water in the fuel oil. 

a. Possible troubles: 

1. Improper performance of the settling tank. 

2. Failure to use centrifuge with sufficient 


3. Leaks in the bunkers. 

1KS. Air or gas in the water. 

sl. Possible troubles: 

1. Cracked cylinder liner. 

2. Leaky pump. 

3. Failed gasket. 

4. Cracked cylinder head. 

1K6. Metal particles in lube oil. 

a. Possible troubles: 

1. Failed bearings. 

2. Chipped or broken gears. 

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A. POSSIBLE trouble: 

Two sleeve type bearings support the rotor shaft. 
The thrust bearing absorbs the force exerted length- 
wise along the shaft by exhaust gases striking the 
turbine blades. These bearings have drilled holes for 
the passage of lubricating oil. 

Damage to these bearings may be exhibited by 
vibration of the unit, damage to impeller or turbine 
blades, an increase in lubricating oil temperature 
(when an independent lube oil supply is used); or may 
be revealed by examination of the bearings when the 
turbocharger is disassembled. 

The bearings should be examined for pitting or ex- 
tensive scoring and for proper clearance, as specified in 
the instruction manual. Shaft end play may be checked 
with a dial indicator by moving the shaft axially from 
one extreme position to the other. End clearance 
greater than that specified in the instruction manual 
indicates wear of the thrust bearing. 

1. Causes and prevention. Damage to bearings usually 
occurs as a result of : 

a) Insufficient lubrication. 

b) Unbalance of the rotor. 

c) Operation with excessive exhaust temperature, 
(a) Insufficient lubrication. The high temperatures at 

which these bearings operate make their lubrication 
quite difficult. An abundant flow of cooling and 
lubricating oil must be maintained to avoid softening 
and resultant failure of the bearing material. It is 
readily seen why bearing failure is generally due to an 
insufficient flow of lubricating oil. 

Some turbochargers are equipped with a lube oil 
pressure gage which provides an excellent indication 
of the condition of the turbocharger lubricating sys- 
tem. A drop in this pressure below the value pre- 
scribed in the instruction manual is a certain indica- 
tion that bearing failure is imminent. The engine 
must be stopped immediately and the cause of lowered 
oil pressure determined. 

Lubrication difficulties may be due to: 

(1) Failure to prime the turbocharger. In some 
models, difficulty may be experienced in failure of the 
turbocharger oil pump to develop pressure quickly 
enough when the engine is started to prevent bearing 
damage. Leaky pump suction check valves may be 
responsible for this. Hand priming pumps are used on 
some installations. In others, it may be necessary to 
prime the pump by pouring oil into it. 

(2) Low lube oil level. When a separate tank is 

Digitized by GQoQIC 

provided for the turbocharger oil, it must be main- 
tained at the level specified in the instruction manual 
to prevent loss of pump suction. High oil consump- 
tion may sometimes be traced to poor condition of 
the oil baffle. 

(3) Clogging of lube oil passages. Swab out all oil 
passages when the turbocharger is disassembled. 
Never use wiping cloths, paper towels, or waste for 
cleaning, as the lint and fiber particles quickly clog oil 
passages. When the bearings are provided with oil 
holes, make certain that these holes are properly 

(4) Clogging of the turbocharger oil filter. Al- 
though a protective bypass valve may be installed 
around the filter, it should not be depended upon to 
prevent damage when the filters become clogged. 
Inspect the filters and strainers frequently, and clean 
or replace when necessary. 

(5) Pressure relief valve stuck open. Some turbo- 
charger models are equipped with a valve designed to 
maintain proper lubricating oil pressure. Sticking of 
this valve can best be prevented by thoroughly clean- 
ing it. 

(b) Unbalance of the rotor. This condition causes the 
bearings to be overloaded, and is usually exhibited by 
excessive vibration. Unbalance may be due to dam- 
aged turbine wheel blading or to a damaged blower 
impeller. If rags are carelessly left in the air silencer 
after cleaning the blower, they may become lodged in 
the impeller and cause unbalance and consequent 
vibration. This can be avoided only by careful in- 
spection of the air silencer and impeller housing for 
any tools, rags, or parts that may have been left there. 

(c) Operation with excessive exhaust temperature. The 
maximum safe exhaust temperature for turbocharger 
equipped engines is specified in the instruction manual. 
Operation at temperatures above this value generally 
causes severe damage to turbocharger bearings and 
other parts. The source of excessive temperature must 
be determined and eliminated. 

2. Repair. When clearances exceed those specified, 
bearings must be replaced in accordance with the 
procedure described in the instruction manual. In 
making replacements, care must be taken to insure 
absolute cleanliness of all parts. Small particles of 
grit, metal, or similar substances left in or about bear- 
ings will cause scoring and necessitate another bearing 
replacement after a short time. The extensive nature 
of this work makes it desirable to do the job well to 
prevent an early recurrence of the trouble. 

Other parts of the turbocharger should be thor- 

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damage TC.KWNfi bidding in lasting tor balancing, wi th crosioo. : •. | 

— ; Broker, or d«»r«d turbuic Wades cause vibration of 

Turbmc Wades Are kcyod and psentd Into the rowt the. turbcichargrr when the engine is operating. Some- 


(c) Failure of bearings. In certain instances, bearing 
failures have allowed the shaft to drop or move end- 
wise until contact between turbine blading and other 
parts of the turbocharger occurs. (See Section 2A2a.) 

(d) Failure to drain turbine casing. Water accumulates 
in the turbine casing as a result of condensation when 
the engine is cooled. When the engine is alternately 
started and secured at frequent intervals, accumulation 
may be sufficient to allow contact between the spin- 
ning blades and the water. This can cause the blades 
to fracture. The turbine casing should be drained be- 
fore starting the engine. If the collection of water 
appears to be excessive when the casing is drained, 
there may be leakage from the cooling water passages 
in the turbocharger case. The case should be inspected for 
cracks, and gaskets and grommets should be replaced. 

(e) Introduction of foreign bodies. Many failures have 
been caused by welding beads or slag breaking loose 
from inside the manifolding. When these small beads 
hit the nozzle ring and turbine blading at high veloc- 
ities, they can cause serious damage. It is advisable to 
inspect as much of the interior of the manifold as pos- 
sible, chipping any loose, or potentially loose, beads 
and removing them. It is important that every pre- 
caution be taken when reassembling to insure that no 
gasket material, bolts, nuts, washers, or other foreign 
matter is left in the manifolding. 

Failure of exhaust valve or valve guides, involving 
breakage, has frequently caused turbine blade break- 
age when fragments of valve or guides were blown 
into turbine blading. After any valve failure of this 
type, stop the engine immediately and thoroughly 
inspect the exhaust manifold and passages for any 

2. Kef air. If one or more turbine blades are found to 
be broken or cracked, or if lashing wires are broken or 
loose, it is generally necessary to replace the entire 
rotor assembly. This includes the turbine disk and 
blading, rotor shaft, and impeller. 

While the rotor assembly may not be a shipboard 
spare, spares are on hand at the shore base. Should a 
spare not be available and an emergency condition 
exist during which it is absolutely necessary to oper- 
ate the damaged engine, it is sometimes possible to 
block the rotor so it will not rotate, or to remove the 
rotor and seal off the turbine bore, and continue opera- 
tion at reduced power without the blower. The in- 
struction manual generally contains all necessary 
information relative to such emergency procedure. 

It is not practical to attempt to repair damaged 
blading by removing the damaged blades and inserting 

new ones. The rotor assembly will operate satisfac- 
torily without vibration only when it is accurately 
balanced. In order to balance the rotor assembly, 
special equipment is necessary, to determine whether 
or not there is any unbalance, and if so, of what mag- 
nitude and what position. 

Often it is thought incorrectly that a slight unbal- 
ance is of no great consequence. An unbalance of only 
one ounce at the tip of a turbine blade will cause a 
vibrating force of almost one ton when the rotor is at 
operating speed. Vibrations such as these are respon- 
sible in many cases for bearing failures, damage to 
impeller, and further destruction of turbine blading. 

c. possible trouble: 


The function of the nozzle ring is to direct exhaust 
gases at the proper angle to give the most efficient 
"push" to the turbine wheel blades. 

Damage to the nozzle ring may be recognized when 
the turbocharger is disassembled for periodic inspec- 
tion. It may be necessary to wipe deposits from the 
ring with a cloth to reveal small cracks. It is impor- 
tant to recognize cracks in their earliest stage if com- 
plete wreckage of the turbine assembly is to be avoided. 

In some cases, large chunks have been broken from 
the outer periphery of the nozzle ring, thereby causing 
considerable damage to the turbine wheel. 

1. Causes and prevention. Frequently, damage to the 
nozzle ring is associated with damage to the turbine 
blading. Causative factors include: 

(a) Operation with excessive exhaust gas temp- 

(b) Breakage of turbine blades. 

(c) Introduction of foreign bodies. 

(a) Operation with excessive exhaust gas temperature. 
See discussion of operation with excessive exhaust 
temperature, page 14. 

(b) Breakage of turbine blades. When turbine blades 
break loose, it is likely that extreme damage to the 
nozzle ring will be found. Contact between the nozzle 
ring and turbine wheel will cause damage to both 
parts. See page 14. 

(c) Introduction of foreign bodies. Any foreign bodies 
that enter the turbocharger with the exhaust gases 
may easily become involved between the nozzle ring 
and turbine wheel blades. (Sec discussion of intro- 
duction of foreign bodies, page 15.) 

2. Repair. Complete replacement of the nozzle ring 
is necessary when cracks are discovered. Continued 

Original from 

Digitized by 



•• .... ■ 




s ■ • few 


2A3,. Jtedfc ryp<rbiowerav .Roots type hiow^sare I'M 
postuive displacement air pumps, used to supply scsrvr 
\-Mging.airto-thccn i ginecy)inilcfs. Tbi* type of b!w 
cami£& of two parallel maitiiobe rotors, the hSuwet * 
i ihft drive- #e;irs; A* the mtnrs revolv^i the: 


? a* 

S - V: 

blowers are equipped with a set of liming gears to \; ; l'/;^ 
drive and synchronize ife rouuoo of r-hc rotor*. . 


~ - • 

On, of the most .mpomm parts of a Roots rype 

1 H 

blower is the set of gears that drives and synchronize* '^SJI^ # * <N ^ 
Ac rwo rotors , Sarisf a «ory opc«t V D ,»-4epcndsni: 

.uponthrcondir.onafihcsc^ the We of *fae gears and deternurie whea tt will be 

Worn gear, ace found b* anuria* the feckUfctf » replace then*. 

lhc ?t ^ GC " r " Wnb " KKkUh 2.. «**. Timely replacement of the Mowe* drive 

specified uvfhe mon^anee a»d mtrmtxm mmiiak: ^. will etiavi 

iisnk of fracture must be replaced with a new set. 

. •■ . . -. - • ' -- • • • • 

: M the rotor .U>Ke* ard rhe . h a y* accurate! \ 

aan! die casing h*v* accurately 
|jjf iio^hed surfaces. This is rkarssary in order to establish 

/ : : > he --lose cIc iraiK^ between ;be rmuoog parts. 

' When clearances are out maintained between rbe 

v " blower- ram.' r he rotor "lobes, coming into c&macc 

. with eacft o 


other or with the casing, soon feeepme--..' 
"igurt 2-7). 

The .scares Yescmhle a smear of the metal. The 

HBH warenai -at thsct point of contact becomes heated, dn^ 

; to impact ai.d fricnoA. The relative motion of the 

fr*\ ™-' part^ Mien wipes ;»*d xir^gft it our of pohtnon^meiring 

RffW 3M. a^i»9 fcinkfqi* offbfor ic Piltn/J it up or, , tradmg surface- of the rotor, 

.twa'dft^iw.-reaainfis is the value of the backhuh L _ W teHMm Wed rotor, lobes are 

interference between rotor lobes, one coming into con- insufficient !ubnau%-<rii. improper bearing .adjusc- 

figor* Chicking chorea of BooH f&* Mow* hb«u 

Should tbe clearances be i 

be mctfrrcct, it Will be neces- (d) Impryptr.tnd diar&no Ipipi^per. rotor end ciear> 
• a to determine the amount of aoces wilt nime poor o^auon. Should the end 

clearance be' in^udic icru\ it : \$ probable* tbm the ro.tor 
tfsivc, if 'will be wUJ rub and ' Ktfrt the end places Rotor end clearance 

s /if rtfffm> tnrlt- imifcV '..thtx-ii&A. &ith lime nf h^r mror H^Mn.v* ^ 

backlash due to drive gear wear 

If the amount of backlash is not excessive, k wdi be wUJ rub and Ktfrt the < 

accessary to retime: the rotors. Methods of tmdn^fod^ aust b* chested time ot 

vidua! makesnf blowers arc outline J in rhcjnscruction inspected, 
manual^ Should backlash be excessive, it will fiw In most Rooin tvpe blowers , the end clearance ad> 

(c ) lU(jr?n : i failure. 'Bearing fojiurcs vvit) citii^e ihc t?Weerj the: end plates and the rase and also behind the 

1 ^ ™s* be taken not -to 


. Many new .oil. seals arc 

necessary w eqnip the end of each ibirfe vmlv oil seals.. ^ J1UMm £ the blower, 

T*~ oil-** i» ,:h,*»,i r i«* 1 *« J -""' c ."= sMl f"'^- 

p.™ The u„ „ b « » f *■ * r^-r ■ 

tJut j v generated. New oi£ seals should be $\ 
clean light lube oil lor about un hour before assembly. grcoh 
J ) Pett hearings* Bearing failures m general acd ' . £ 

soaked in is ukt-n m Joints so the possibility of tnimc will- be" 
as*cmbly «re,«dv dcn*ca&cu\ 


■ — — -T.-r:-- >r T.: ? fig — ' 

(a) Failure to inspect. 

(b) improper select ion of pswrt$- 

id Faihrr to tmpect. Total shall biltire is caused' by 

checked m see thai rhev in snugly and chat there is no ; : 

indication of excess o. e t.vcar. 


»**■ sT*< 



(b) C#?$kii mxtatl#tian vf manifold Akfaougb pre- (£) Obstruction in air box or separator ■ drain. Certain 

witft ratal cnvps or mn& mmm pamcm m tncm. putty c*r craniccase erosions, .venwxn cat mokxase. 

Personnel *bou)J $*i th*r protective flanges on new This is sometimes accomplished by a parage bfctweco 

manifo^ time ;vi msUlU- ' the cninkcasc and the intake -$ide. ofxhcklow?f* 

nor only protect the foanifoki flange faces against the blower, forced into $be zogiiu; cylinders. ?nd 

2C1 , Ebclrkjal a« 



■■^V : &^M^ : ^'-- : wM ft 


v . .•'•/'.' v:/ |l - •*•"••••■■/•••.• • • • . I • 

2G2. flame primers for drt 'kiqHim. FUnae" pritaers gap reset. Other troubles ijacitsdc hul ty wiving, 
burning dicsel ftid placed in the air boy or mini- switch, pr spark evil/ toil failure oeccssi rates its 
fold are .nmetimts used tr, hear rhe imake :ur . The ^l aM .m^..ik« J il rewinding is nor mattiral 

or viscous,, ty#e air ctegmr and tifeflcw, 

viscous, i 

^ (C) : JFautty pressure pomp. rhmu^h a tme mesh to <dter or sir 

attributed to the spurk coil vibrator. Corroded or wound ovpptr enrop, or 

- - 


with a medium weight oil that holds the dust and 
dirt which is collected. 

a. possible trouble: 
clogged and dirty air cleaner 

Clogged and dirty air cleaners will cause hard 
starting, loss of power, poor economy, engine smoke, 
and overheating. 

1. Cause and prevention. It is essential that air 
cleaners be serviced at specific intervals as stated in the 
engine instruction manuals. Failure to do this will 
result in clogged cleaners. 

2. Repair. The clogged filter should be cleaned 
either with diesel fuel, gasoline, or kerosene. The 
filter should be removed from the engine. As the first 
step in cleaning it should be blown out to eliminate all 
loose dirt. Next, if the cleaner is sufficiently small, it 
should be submerged completely in the cleaning sol- 
vent. Otherwise it will be necessary to apply the 
solvent with a stiff brush. 

The filter should then be blown out thoroughly 
with compressed air, and a medium viscosity oil 
should be applied to the mesh. 

b. possible trouble: 
explosion caused by volatile solvents 

used for cleaning 

1. Cause and prevention. Volatile materials such 
as gasoline and kerosene do an excellent job of cleaning 
the filters but their use may result in serious explo- 

sions. When volatile solvents are used, it is of utmost 
importance that the filter be blown out thoroughly 
with compressed air before being reinstalled on the 
engine. If compressed air is not available, the filter 
must be allowed to dry for several hours. 

2D3. Oil bath type air cleaners and filters. The 

oil bath type of air filter employs a pool of oil upon 
which the dust-laden air impinges. The inertia of the 
dust particles causes them to strike and then adhere to 
the oil surface. Oil bath filters usually have screening 
and metal wool in addition to the bath to help remove 
the finer particles. 

a. possible trouble: 
excess oil in cleaner, causing engine to run away 

With the oil bath too full, the intake air will cause 
the oil to be drawn up and taken into the cylinders. 
There is obviously no control over the amount of oil 
which enters in such an event. Thus the engine is 
liable to get out of control and run away, resulting in 
possible damage. 

1. Cause and prevention. After cleaning bath type 
filters, there is a tendency, when replacing the oil, to 
fill the bath too full. 

When filling oil bath containers, it is important that 
they be filled only to the FULL mark, as indicated on 
the container. Filling beyond this mark will not in- 
crease the efficiency of the filter. 

The oil should be changed when dirt begins to 
collect on the bottom of the container, or when the 
oil thickens. 


26 Original from 


... • . iici''V'. f !>• -a **j • ■ 
• J* • •• • 

'6 VV/.'.y i. :.V>" 

V I if - 1 

3A1. tfe-atbaw ^tcm includes chacked MANt rou> 

^se ^mpiments of ihc/tngioc/^h^e'farsctitm'Js- to Tbis troubJc may h^ome apparent through Jcakagc. 

is tiQt advert }v affected, water may drain into the cylinder and be trapped 




in ke watet, it ttsuaJjy' shatters. Similarly, if tempera cures to exceed 130*?*-- The. rate of pr£eipira- 


. ~ -h y V - siKc^s^i-tifiJesb' ^formed by an expert, 
cured; char lS> if it has 

t pro! unged opera tiofl n cii PfsjTFP 

at high load*, Always the load oa thcmgmc m ■ * ^LtrNvLK 

before, securing: us an aid to gradual cool rng/of'eogi&e 381. taftodutfion, Exhaust silencers or mufflers 

p. xr ^ 1 ; C reduce irh.c noi.^r of vlicsel engines^ This is a military 

>KU>^^ oecmtty, Also, the rcduaioa m mm level adds to 

i*rv^al itr^k^: fir <^*r . ' *f i^nlr! *v* : ±irr(M* the Cqtafort of. personnel 

I « 

type rrmrBer. 

f . 'j • 2 - ' . " • ^ ^.^ ^ f Mies and t ortuous passages of the dry t T 

#9W0 ' " ^ °* A. POSSIBLE T«UtJBLE: 

- of • • — — " 3 W^ K ~t A -.z . u \ 1 ' * N I - t i_? NrG1 ^i E .._. 


If water is introduced inco cylinders, if tvii] $pray (b) Improper c 

forth train open indicator cocks or injector we Us when (e> XV 

the engine is barred over pre punt to ;ry tu mttm^. Ji (Vfte/^^^ w 

Mm restricted; ; 

&*- M Ji S*.\t<* m< r *r.- Av^.'./.i'no J 

On turhoGharged eogipes, salt «atK .may mtro. To correct *his condition, there are several aitcrna- 
dueed from the nia/fler into -the exhiutsr gas carbine. rives: 

mst manifold 

The high tempera tarts therein cause prmf nation of (1 
salts on blades and shaft, in seyer^ the turbo- -"'^ 

■liirgsr ha>; been that 'is, it ha* cosed to curav 

Corrosion irf exhaust 

- — —7—* • 

Mb'F f i-ER ' ' ^ 


feasible and is generally considered undesirable. 

(3) Reduce the quantity of water injection. It must 
be remembered, however, that a reduction in water 
input will increase exhaust noises, and increase the 
tendency toward steam formation, overheating, and 
corrosion. Therefore, the amount of water injected 
must not be reduced to such an extent that silencing is 
inefficient or visible steam is formed. 

To reduce the quantity of water, bypass a portion of 
inlet water overboard as shown in Figure 3~5, or 
place a throttling valve in the inlet water line as 
shown in Figure 3-6. 


OAS • 




Figure 3-5. Use of three-way proportioning valve to 
regulate water flow to muffler. 






Figure 3-6. Use of throttling valve to control flow of water 
to muffler. 

If these steps are not practical in some installations, 
a muffler of different design or dimensions may be 

Since corrosion is usually accelerated by reduction 
in cooling water flow rate, the muffler should be 
inspected frequently for signs of corrosion. 

(b) Improper design. On occasion, mufflers not prop- 
erly designed for certain types of service have been 
installed on marine diesel engines. In heavy seas, sea 
water has been forced back through the exhaust 
system into the engine. If alterations to piping fail to 
stop backflow of water, it may be necessary to replace 
the muffler with one of improved design. 

Digitized by 

Go gle 


(c) Water drain restricted. In some wet type mufflers, 
continuous water drains are incorporated. Only a 
portion of the water injected into the muffler is carried 
out by the exhaust gases. If this water drain becomes 
clogged or restricted, water will accumulate in the 
muffler. In some installations this water will flow 
back into the engine. Keep drain lines free from 

2. Repair. When presence of water is detected in the 
engine cylinders the source of the water must be 
determined and the cause eliminated. Remove water 
from cylinders by opening the indicator cocks, or 
removing injectors when no cocks are provided, and 
then cranking the engine slowly. After removing the 
excess water in this manner, crank the engine rapidly 
until all traces of water are blown out. 

When water has been discovered in the engine, 
always check the lubricating oil thoroughly for traces 
of water. If water is present in significant amounts, 
drain the crankcase thoroughly and remove the water 
from the oil by settling and centrifuging. If a centri- 
fuge is not available, drain, and replace the oil with 
fresh water-free oil. 

b. possible trouble: 
corrosion of muffler 

Salt water in hot mufflers has a decided tendency to 
corrode them. This trouble may be recognized by 
pronounced pitting of the inner surface of the muffler. 
In severe cases the trouble may be detected by leakage 
of water and gases from the muffler. Any uncoatcd 
iron exhaust muffler may be expected to corrode and 
become unserviceable after extensive usage. For this 
reason, it is advisable to inspect mufflers frequently so 
as to have a replacement muffler available prior to 
failure. A leaky muffler can allow sea water to spray 
over electrical equipment with disastrous results. 

1. Causes and prevention. Corrosion of mufflers may 
be accelerated by : 

(a) Burning off of protective coating. Some wet type 
exhaust mufflers have been coated internally with 
corrosion resistant material. Certain types of protec- 
tive material are unable to resist the temperatures 
present when water circulation in the muffler is 

If the sea water flow is interrupted and the engine is 
kept running, the protective coating will be burned 
off. This exposes bare metal and results in rapid de- 
terioration of the muffler. Consequently, it is impor- 
tant to maintain water circulation in wet type mufflers 
whenever the engine is running. 

Qrigiral from 


2 Repair. When a leak in the ; :mu'fflcr is recognized worn .pi's too. rings, loose bearings, or at her faults rhat 

inspection and cleaning. Mu filets sbnuld -be drained .wirer tnro che jaufllcr. | the corrosion rate appears 

of oi! accumulations a r regular interval*. During excessively rapid, th^ cause muse be invesr^ated and 

per rods of prolong «d)mg, inspections should be eliminated 

made more frequently as acroimibnon is most \tkch (fa) F^Uurr to imu 

m occur at these times. are subjected ro h.ig 

(b) iW Wdttion «t*«*in* If ftft ™<r,fi, tvlirn hr 



\ • < * /« * " ...... \\ -V, ° 

Figun 3-8. fare. p«d^ .^ ,^U^f piping b ¥ th**m*l 

thermal expansion of sred pipe fs approximardy WO vided to absorb elongations of piping caused by 
nnuti^^ r>c(- Na-ii;irc .rich of Thecal cmss~Sec*tOn-ai artiiL. increase* in tdiirn<:.rj.tnfe. in smile in&taliatirms water 

of pipe WOUid t>c about n/16-inch. if ho expa^- - 

strong^hc^^iision mav roulf .« broken or leak ing caa5e ^ incr ^ ia the Exhaust Uumiold pressure, or : 

ppe connection*. To prevent chi* damage, the ^ jtauw* on the engine, 

'cable expansion rmm be aborted by expansion This^cirasc in back hrcssuiriftate it more difficult 

.or bend., Space Kimwioii* aWi abip usually for chc e .ng ? nc cylinder to be purged eompJctdv of 

te jomu rather than bends. txUjxxsi z&c^ and prevents complete t^Maim ot 
Mmi ?%\\immv)oit\i$ also provide $We. degree 
■flexibility, and thereby reduce vibrutitm rransirrnssi 
l V o- r .. • f . . . . r r , . * a 


J Causts md pmnmn. The usual causes of this &rram critical och^ st pi|,e kngths prtywt proper 
trouble are: silencing. Io.-itfcfi cases, a shgbr increase or ifccwsc. •• 

/•-> i~J.M-.j~~ in niptnfi J«ieth mav soJVfr fhe¥kocin* tumble®-. The 

(a) Improper 

(b) Accumulation u 
(a) Imprapur instultetian. C 

installarfofi arc-: (.1) &ri#gx ^ diamtut is too small. tacturtf ss to ™ e P*?F* W» cm pi 

As explained before, an exhaust pipe of too small a ^ tbc iikneer. Tail pipe lengths s 

diameter will not cam- the required quantity of ex- ia th « ^ of chsn in 

haust gas from the engine- without inducing excessive wct 
, back pressure on the engine. ' W /« 

i R ----- - ^ 

mm m 

Considerable lociimuhraon ot sajts, or scait. ,o 

exhaust \m fittings may. be the resujt of trapping of 3C1 Stock. Most diese) engines' equipped with 

Water in these ntti.i.fis. . dry type mufflers have exhaust stacks to conduct gases 

/ IntheOtfetUustrarcd by Figure 5-1 2, the elbbw sags away itrr/m the ship In stacks serving u.ore than one 

below other non sons of the oipioe and allows water engine, the exhaust >■ -'-■■ 


A. POSSIBLE trouble: 

Corrosion of the exhaust stack may be noted by 
inspection of the exhaust stack. Patches of corrosion 
may be found near the top of the stack or at the bottom. 

Corrosion at the top of the stack may appear as 
streamers which diminish in width toward the bot- 
tom of the stack (see Figure 3-13). 

1. Causes and prevention. In the case illustrated in 
Figure 3-13, the cause of corrosion was improper 

design of the stack, resulting in condensation of water 
from exhaust gases on the relatively cold unjacketed 
portion of the stack. The water drops formed there 
absorbed sulfurous gases and formed acid which at- 
tacked the stack. The peculiar pattern formed was a 
result of evaporation of the acid as it flowed down the 
inner surface of the stack toward the warmer zones. 

2. Repair. This trouble was overcome by extending 
the air jacket up to the top of the stack, as shown in 
Figure 3-14, thereby eliminating the relatively cold 
band at that point. 

Digitized by G0O 




Digitized by VjOUyiC ^ 



ion 1. ru 

^Sii . 11 ' . • lis 




r j 

'O.i. /: tt _>'«■ yu'i *0 <Tf4,^rv f .T v OnT OOi E ACH sf.'rfe SiOf '. .,»••.-. 

- to 





- ; . 


Low fikl pressure can often be^. to rhc spring 
tension setting on the 'pressure by pjss \aIv*> This may 
be corrected -fey' righ cening down die aaju$ciog screw. 
However, before mak itsg the a J jmcrotn r v ii t$ flutes- 
sary "fhat the spring arid check ^lv? be inspected. Hie 

fad lojccror 
engine rwssm^. 
from running ut a J I 

■ ■ . ■ • 


if'hichrhavis .heten-kiitlieiA masr he. 

Deformed'. Hats- which ■;'ha:vt:.b^ : :-'jfffik^; ; jn!Hist 

I L't 

p:> straightened if possible; othtnMSc: tfcey /should be 
replaced- Sccr>Dft& rbaf h.ive Wen straigbteaed most 

, * - ^ • ; ;^«*g th* ourpur ; lr,i*'^«> pMiibte^^whco the 

■ efe^M * pump and seats ^ in wt*m^ poor conditio*, for. . 

|^P^^^fPP^7 * * y^p^^^Sr I ait to be draws* roro the pump past che.scais. 

pump past the seals, 


note. The pump used oh these 

from th6pLunp may decrease the deliver}-, 
mice ikies \vi» Jtmit the fuel supplied K> «he pu 

R P s t n«eU outlet will caosc UmiceJ Jl WW hv caus- (U) H^«*;, * %. Thecucucpamp 

j^j : t|iw« of the fad co b<r n^ifcuht^ ' tb**Hi£h the' 'assembly i.?ui;>r. be vbaU.-i p*m»dic,.> ! i.' co dewmioe: 

bushings should berepliap 
use will c^use d 


ouldbcrqil'accdiraraedtiitdy, as continued sizes, with or without n hand priming ;/ for 
sc damage to the rotor and pump body, manually priming the fuel supply lines before starting-, 

Rnc<-Vi mom'ne »»'nf*li« «• u-i<tkl» emit-*. wlfowii^JiiJil'ii 

possible to repair satisfactorily ,t faulty pump Worn 

«cott«K« apparent, a rte,V; P iur, r , ifouLi be Stalled on ^fe^E^ ifefe 
the engine. 


4Ct, Gwwal, Two pfqngcr type pumps of diflpr- 
esu manufacture are shown below. Figure 4-8 is the 
Bosch; arid Fte.urc <?-9, the Exceljo. 

a . | '* « ». j 

pumps of dtfier- g 4| § 

igure 4-8 is the S^S 

FtG- A 


; '■:';^':- , :''.f" *': - 


■ * of the supply pump io the inlet side of the injection 

pump. The stroke automawcaUy proportions the 
quantity of fud deliver^ 

plus fuel to the supply unkV The ovoilaVv ^ittvt is 


dressing down the valves, and care must be taken to 
keep the valve flat. 

Pitting of the valve seat and excess wear on the fibre 
valve is usually the result of small particles of dirt 
which have been caught between the valve and the 

(b) Broken plunger springs. Broken plunger springs 
will cause complete pump failure, as this spring sup- 
plies the returning force to the plunger on its delivery 
stroke. Weak springs make the pump incapable of 
supplying sufficient fuel at maximum load. They 
should be replaced upon discovery. Weak or broken 
springs are caused by fatigue of the spring material. 

(c) Stuck push rod or plungers. Some poor grades of 
diesel fuel cause resinous deposits to become lodged on 
the parts with which the fuel comes in contact. Such 
deposits are capable of causing the plunger and push 
rod to become stuck in the depressed position, thus 
preventing the discharge stroke. Such resinous de- 
posits also have a ruinous effect on the plunger, barrel, 
and delivery valve of the injection pump as well as on 
the injector nozzle assembly. 

2. Repair. Care should be exercised during all re- 
pair processes to keep the parts clean. A bath of clean 
fuel oil should be used to cleanse them. It is custom- 
ary to assemble the parts wet, thus allowing any 
foreign particles to be rinsed off immediately before 

4C3. The Excello fuel transfer pump. The Excello 
pump operates similarly to the Bosch pump previously 
discussed, with this exception: the discharge valve is 
contained in the plunger itself to facilitate the transfer 
of the fuel from one side to the other. Troubles oc- 
curring in the Excello pump are identical with those 
encountered in the Bosch supply pump. The design, 
however, does not lend itself so well to repair as does 
that of the Bosch transfer pump. 

If the fuel pump fails to operate, it should be re- 
moved from the injector pump housing and submerged 
in a bath of clean fuel oil. With the pump submerged, 
operate the tappet by hand. If the pump discharges 
fuel from the outlet, the valves may have been dirty 
and are now clean, or there may be an air leak around 
the gasket of the pump body. Usually, leaks may be 
stopped by replacing the gasket. 

If dirt, caught under either of the valves, is causing 
the pump to be inoperative, it is usually possible to 
remove it by blowing compressed air, not in excess of 
40 psi, into the inlet connection. 

Digitizes by CjOuQle 

Section 2. Injection Pumps and Nozzles 

4D1 . Functions of the system. The fuel injection 
system may be considered the heart of a diesel engine. 
It is the most intricate of all the systems, and requires 
special care and precautions when making adjust- 
ments and repairs. The function of the fuel injection 
system is to deliver fuel to the engine cylinder under 
the following specific conditions: 

At a High Pressure 

The system must increase the pressure of the fuel to 
the extent that it will overcome the compression pres- 
sures within the cylinders, and, frequently, supply the 
added force necessary to atomize the fuel completely. 
This requires that fuel pressures as high as 5,000 psi be 
maintained in some of the installations. 

At the Proper Time 

The fuel must enter the cylinder at the proper time 
in the engine cycle in order to obtain proper combus- 
tion and maximum energy from the fuel. In many 
cases it is also the function of the pump or nozzle to 
vary timing as speed or load varies. 

In the Proper Quantities 

A third function of the fuel injection system is to 
meter the fuel. For smooth and even engine operation, 
and to insure an even load on each of the cylinders, it 
is essential that an equal volume of fuel be admitted to 
any given cylinder each time it fires, and that equal 
volumes of fuel be delivered to each cylinder of the 
engine. An additional requisite of the metering sys- 
tem is that the amount of fuel being delivered be 
varied to allow for changes in load and speed. 
Properly Atomized 

To burn efficiently, the fuel must be distributed 
properly throughout the combustion space, and, prior 
to combustion, must be in a finely divided, or atom- 
ized, state. 

4D2. Types of fuel systems. There are three gen- 
eral types of fuel systems that have been devised to 
perform all the functions required, they are: the jerk 
pump system, the common rail system, the air injec- 
tion system. 

An example of the jerk pump system is the Bosch 
system. The Bosch pump is a cam actuated, constant 
stroke, lapped plunger and barrel pump. The pump 
times, meters, and provides the necessary pressure to 
inject the fuel into the cylinder by a separate nozzle. 

Another example of the jerk pump system is the 
General Motors unit injector. The unit injector em- 
bodies a cam actuated, constant stroke, lapped plunger 
and bushing high-pressure pump, and an injection 

Qrigiral from 


nozzle, all in ooe am r. The unit injector fulfil Ik all rhc ; mixing «tnd providing rurbulcnicc. This system- re- 

system Mounted m each cVli'ndct bead is 3 cam actu- power rcq lined rodn.Veit J^sems .the usefulness of this 

ated injector and nozzle th»c iftfca the fud into the type af system Eo.jdd>ti(m. tkr atradmuied ta the 
cylinder. This system employs a common metering / ... cylinder rend'; n> IcnnCu rhe compression, tcmjicrarures 

device that distributes a measured quantity of fuel to wr^hiLV the cylinder.; thus t$xAi tig to poor combustion 

each of the ipjtctors. and operation A\Y injection system* are now obso- 

The fuel injection system used on Atlas engines is j ere, and only a few of the Maw's older ships have «ti 

of tbcvtittftftM rati type. fV mplovs one ht£h pressure injection ' cflgiacs, ... 

pump *h<u supplies the tud *t mierrum nrc*«M uv,« ft «\ eiutntiurv to differentiate heivcreen an air mVe^" 

cam operated and tto 
Metering is 
nozzle remains 
The injection system 


gmcs ii a mudihcd common rail system, h uses -one 
high-pre&surc pump chat maintains foe! at the injec- £ g< 
iion pressure in An accumulator bottle. The fuel i$ \ 

metered by valves mounted on thtrsidt-of 4fel. General descriftftern Any ship or station 
the sflcme; and then *oc& to the. pressure operated t^ me Bosch fuel injection equiprnen^'^^Mld procure ?; 



• - ,, •/ ■>■•■■. * 

:.''t >.. ■ Vt.RY 

At-r •' Mi- , f 



Kftcun c ■:■ •••;c- t:-v.. ,i]W»y< begin 5 

bo an-? lap f«»J *hsc <fc»v THM*f< iyp 

When ihe .barrel is examined, search should be 
™ - ™" of the U r pd 


(a) Entry of dirt into the pump. 

(b) Careless handling while disassembled. 

(c) Overtightening of delivery valve holder. 

(d) Corrosion. 

(a) Entry of dirt into pump. Dirt is responsible for 
almost all trouble encountered with fuel injection 
equipment. If pumps are not properly protected 
against the entry of dirt, they can be damaged irrep- 
arably within a few seconds of operation. It must be 
remembered that plunger to barrel clearances are in the 
neighborhood of one one-hundredth of the diameter 
of a human hair. Therefore, extremely fine particles, 
such as dust from the atmosphere, are capable of 
scoring the lapped surface. (See pages 92-97 for 
precautions in maintenance of fuel system protective 
equipment.) The engine should never be operated 
unless the fuel has been properly filtered before reach- 
ing the pump. 

In addition to precautions with respect to fuel filters 
and strainers, it is imperative that cleanliness be ac- 
centuated while working on the pump. From the time 
the removal of the pump from the engine is begun 
until the pump is replaced on the engine, extreme care 
must be exerted to keep dust and dirt away from the 
pump parts. Before any connections are loosened, all 
dirt should be removed from the pump, tubing, and 
fittings by washing with kerosene, diesel fuel, etc. 
After removal of the pump from the engine, all open- 
ings on the pump, tubing, and injectors should be 
covered with paper caps, or clean rags. Whenever the 
pump is to be disassembled, a clean working space 
must be provided. Only clean containers with clean 
diesel fuel or cleaning fluid should be used for cleaning 
parts. Compressed air should be used to blow all parts 
dry after cleaning. 

(b) Careless handling while disassembled. As many 
surfaces on plungers and barrels are lapped to ex- 
tremely accurate finishes, it is imperative that they be 
handled with great care. If these parts are dropped, 
they may be bent, nicked, dented, or otherwise 
ruined. The work should be done well over the center 
of the bench. Hard metal surfaced benches are not 
desirable. A linoleum covering will reduce casualties 
caused by dropping parts on the bench. Parts should 
be kept immersed in diesel fuel until handled. Dry 
lapped surfaces should never be handled. The perspir- 
ation on the hands of the operator is corrosive, and 
corrosion of lapped surfaces will occur if they are 
handled when dry. Before a lapped surface is handled, 
it should be immersed in clean diesel fuel, and the 
hands rinsed in clean fuel. Parts should not be left 
lying around uncovered on the bench. They should be 

Digitized by GOuQIC 

kept immersed in clean fuel in a covered container. 
Mating plungers and barrels should be kept together 
to avoid interchanging. 

(c) Overtightening of delivery valve holder. It will be 
noted that the barrel is held in place by the delivery 
valve holder. Overtightening this holder will distort 
the barrel, causing scoring or excessive wear on one 
side of the plunger. A bent plunger will wear in much 
the same manner. A wrench should never be ham- 
mered to tighten the holder. The proper size wrench 
should be used for tightening the holder and maintain- 
ing delivery valve gaskets in good condition. 

(d) Corrosion. Water in fuel oil, improper storage of 
pumps, or handling dry lapped surfaces with oil-free 
hands, can cause corrosion of plunger or barrel. All 
fuel should be centrifuged, and filter cases drained 
periodically to prevent excessive collection of water 
(see pages 92-97). For proper storage procedure, con- 
sult the Bosch fuel injector maintenance manual. 

2. Repair. Damage to a plunger or barrel generally 
requires replacement of the parts. A plunger or a 
barrel cannot be replaced singly. A new plunger and 
barrel assembly must be installed. Pits, or rust on the 
flat lapped surface at the end of the barrel adjacent to 
the delivery valve, may be removed, if not too severe, 
by lapping on a surface plate with lapping compound 
until the pit marks or rust are not visible. Otherwise, 
the plunger and barrel assembly must be replaced. 

b. possible trouble: 
external leakage from pump 

Unless the operator is attentive, and the engine is 
kept wiped down, a leak sufficiently large to affect 
engine operation may develop without his knowledge. 
When the engine misses, the high-pressure fuel lines 
and fittings should be checked for leakage. The pump 
housing should also be checked for signs of leakage. 

1. Causes and prevention. Leakage may occur as a 
result of: 

(a) Delivery valve holder damaged or not 


(b) High-pressure union nut damaged or not 


(c) Bleeder screw or gasket damaged or not 


(d) Cracked housing. 

(a) Delivery valve holder damaged or not tightened. The 
threads and seating surface of the delivery valve holder 
should be inspected for damage. If damaged, the de- 
livery valve holder must be replaced. When the holder 

Qrigiral from 


is tightened, it should be run into the gasket by alter- 
nate tightening and loosening; the holder should then 
be tightened, but not excessively. 

(b) High-pressure union nut damaged or not tightened. 
The union nut should be checked for damage to threads 
or seating surfaces. If damaged, it must be replaced (see 
pages 94-95 for information on high-pressure lines 
and fittings). Union nuts should be kept tightened, 
as a small amount of leakage will prevent firing of 
the cylinder. 

(c) Bleeder screw or gasket damaged or not tightened. If 
either the bleeder screw or bleeder screw gasket is 
damaged, leakage may result. Damaged parts should 
be replaced and the bleeder screw kept tight. 

(d) Cracked housing. On rare occasions, housings 
become cracked. Housings must not be subjected to 
shock blows. 

2. Repair. Leakage can be stopped either by proper 
tightening of loose connections or by replacement of 
damaged parts. 

c. possible trouble: 


This trouble is evidenced when the cylinder served 
by the stuck plunger fails to fire. Missing may be 
intermittent if the plunger sticks and breaks free at 
intervals. Upon disassembly, it may be difficult to 
remove the plunger from the barrel. In some cases, the 
plunger will stick when the pump is assembled but 
will work smoothly after disassembly. In other cases, 
after the plunger barrel assembly is removed and the 
plunger is replaced in the barrel, it may be difficult to 
remove the plunger from the barrel after the assembly 
has been out of the pump for awhile. 

1. Causes and prevention. A plunger may stick in the 
barrel because of: 

(a) Dirt or gummy deposits in pump. 

(b) Distorted plunger or barrel. 

(a) Dirt or gummy deposits in pump. Particles of dirt 
may become lodged between the plunger and barrel 
and interfere with or entirely prevent movement of 
the plunger. Lacquer-like deposits, from fuel, on the 
plunger or barrel will likewise interfere with movement 
of the plunger in the barrel. The fuel system should 
be kept clean and all cleanliness precautions observed 
when working on the pump. (See a) Entry of dirt into 
pump, page 46.) 

(b) Distorted plunger or barrel. Slight distortion of 
the plunger or barrel will result in binding. Usually, 
unless motion is entirely prevented, there will be 
evidence of local wear on one side of the plunger. Dis- 

Digitized by G(X 'flic 

tortion may result from dropping or striking the 
plunger or barrel on the deck or other hard metal 
surface. Distortion of the barrel may result from over- 
tightening the delivery valve holder. (Sec c) Over- 
tightening of delivery valve holder, page 46). In such 
cases, the plunger may appear perfectly free in the 
bushing prior to assembly of the pump, or after the 
plunger bushing assembly is removed from the pump. 

2. Repair. Before replacing a plunger barrel assem- 
bly, an attempt should be made to free the plunger by 
soaking the assembly in some such cleaning fluid as 
specified on page 45. Twelve hours or more should be 
allowed for obstinate cases. These fluids will imme- 
diately soften paints or enamels. Consequently, 
enamelled plunger springs that come in contact with 
these fluids must be replaced. When it is possible to 
remove the plunger, but it does not slide freely within 
the barrel, both plunger and barrel should be cleaned 
thoroughly with an approved cleaning fluid, rinsed in 
clean fuel oil, and blown dry with compressed air. 
Following this, a small quantity of mutton tallow 
should be applied to the sides of the plunger, and the 
plunger worked back and forth while slowly rotating 
it in the barrel. This will remove the gummy deposits. 
Lapping compound must never be used on the mating surfaces 
of the plunger and barrel. If this procedure does not free 
the plunger, it will be necessary to replace the 

d. possible trouble: 


This condition usually causes governing difficulties. 
That is, the engine speed may fluctuate — decreasing as 
the engine is loaded, racing as the load is removed, or 
hunting (rising and falling rhythmically) continu- 
ously, or only when the load is changed. In some 
instances, the engine will not respond to changes in 
throttle setting, and may even resist securing efforts. 
All such conditions can be serious in an emergency; 
hence, every effort must be made to prevent their 
occurrence. The best way to check for a sticky rack is 
to disconnect the linkage to the governor and attempt 
to move the rack by hand. If the rack return springs 
and linkage are disconnected, there should be no ap- 
parent resistance to motion of the rack. 

1. Causes and prevention. A sticky or jammed control 
rack may occur as a result of: 

(a) Plunger stuck in barrel. 

(b) Dirt in control rack mechanism. 

(c) Damaged control rack or control sleeve. 

(d) Improper assembly of pump. 

Original from 

•.>ioa of motion of the vM:k, if a plunger issiuck. The. repeated ^ ohzii as ntc^^xy. 

sticking of one ganger APE pump will hinder or fb) 0*ite<tttUhcty rah* ambly., If sitiier the valve 

prevent motion of the. r,u:k< -which in turn affects the or body is crocked,^c- jiuv occur . Wheu id'- ... | 

rowiou- of 't]>e.p]iifj.^O's. rl»c cm rhc engine*. faUure to. follow 

(b) gjft mM rack mchanism. Metal chips, insoucnom for timing the. pump nwv r^att in severe , ; 
dirt., gam ctc- V.oo the rack teeth or control sleeve danug* to the plunder -and deiiverrvalve A^mbR ff 
teeth mteriVre wkIi movement. of the rack. Care the tanp-t ad laments, on the AI*B p^ntvp 'ate not 
should be tu-ken tocleun ali parts rhorovighly-vvhen the properly nuidei fhe. plunger may strike the -delivery 
pump is ijisa^cmbtcd. valve holder wuh disastrous remits The UMauUc- 

( c) p4>mpd:cotitivl.fa<k ff^^«^/'>/^; /The teeth cm ' filters of die engines oa Which' APF pumps are used 
the'conrrol rack and Control sleeve should be exatyv issue instruciions for the adjustment .of those pumps, 
hied for- irregular i ties ihm toighr cause bind lag. If the In most cases, timing is adjusted bv means ojLs:hiuis 
tack is subjected! to extreme mishandbug, :t may he * between the pump houVmg and the engine mounting 
benr sufficiency to cause fending, Casualties to the flange. In adjusn^ the A pump, f he best prec/m- 
controj rack ate rate and it-; seldom necessary to rion against contact between pbmger ^nd delivery 
replace ic valve- assembly h to make certain thae die scribed 

(d) imprvptr jjsstftbly of th pump. If matching marks timing line on the plunger gttfi* ei^p does tt^t di sap- 
on the rack, s!eeve> and piunger arc not m the proper pear from view through the pump housing inspect i&ii 
relative positions to each other, binding of the rack window (sec Figure 4-17). 


WW, » 

ceasc w operate rmperiy,} WC r,. 

Ca) Dirt or vanish on valve. 
(b) Cracked delivery vulve assembly. 
. (c) Broken delivery valve spring. • ' : ■ ■ '"■ , - , 

(d) Roughened sears. ^H»Mi«p!lW 
(a) /»* or vomtib m valve. Sric kine» of ihc valve is R gure 4-77. 4* p«mp «s>W window. • 

usually due- to a. dirty or varnished valve sea t, rebel 


corrosion. The springs should be inspected carefully 
each time they are removed from the pump body to 
insure that they are flawless. Any spring that is 
nicked or corroded must be replaced. 

(d) Roughened seats. The valve seat and valve body 
seat should be examined with a magnifying glass for 
scoring or other marks that might affect proper 
seating. The flat lapped surfaces of the delivery valve 
body should likewise be examined for similar marks. 
Roughness of the valve or body seats may be removed 
by lapping the valve to the body with a mixture of 
clean diesel fuel and talcum powder. Extreme care 
must be exercised to avoid getting any lapping com- 
pound on the relief piston. The flat lapped surfaces 
may be cleaned up by lapping on a surface plate. All 
traces of lapping compound should be removed from 
all parts prior to assembly of the pump. 

2. Repair. The delivery valve should be checked for 
stickiness, and cleaned up with mutton tallow if 
necessary. Bad surfaces should be lapped as specified 
above, and replacement made of any parts showing 

f. possible trouble: 


This trouble, like stickiness of the control rack, will 
influence governing of the engine. Proper governing 
is based on the theory that for every change in speed 
of the engine, there will be a corresponding change in 
the quantity of fuel injected. This is obviously im- 
possible where looseness or play exists in the control 
rack system. Continuous or intermittent vibration of 
the control rack may indicate excessive backlash. 
However, it may also indicate difficulties in other 
parts of the governing system. The best method for 
checking backlash is to disconnect the rack from the 
governor linkage, and observe whether motion of the 
rack will result in rotation of the plunger. No back- 
lash is permissible. 

1. Causes and prevention. If the control sleeve gears 
are tight on the control sleeve, backlash in the control 
rack may be caused by : 

(a) Worn control sleeve. 

(b) Worn rack. 

(a) Worn control sleeve. Excessive wear of control 
sleeve gear teeth will allow looseness to exist. Like- 
wise, wear of the plunger guide slots will permit play. 
Either of these conditions requires replacement of the 
worn parts. 

(b) Worn rack. As the control rack is quite sturdily 
constructed, it normally experiences little wear and 

666202°— 46— 5 

Digitized by 

Go gle 

seldom requires replacement.. However, if because of 
some governing difficulty the rack is subjected to 
constant vibration, or if dirt is allowed to enter the 
system, wear will be accelerated. Excessive wear of 
rack teeth necessitates replacement of the rack. 

2. Repair. Backlash in the rack is almost invariably 
due to wear of some parts of the pump. Consequently, 
it is only necessary to determine which parts are worn 
and to replace those parts. 

g. possible trouble: 
pump improperly timed 

Early or late injection timing seriously interferes 
with proper engine operation. Early timing may 
cause the engine to detonate and lose power. Those 
cylinders timed early may exhibit low exhaust tem- 

Late timing usually causes overheating, high ex- 
haust temperatures, loss of power and smoky exhaust. 

Ruinous damage can result from improper timing of 
injection pumps. This occurs when the pump is so 
adjusted that contact between the plunger and delivery 
valve holder is permitted. Unusual resistance to turn- 
ing when the pump or engine is barred over cautiously 
may indicate such a condition. 

Timing can be checked readily by the procedure 
given in the engine manufacturer's instruction manual. 

1. Causes and prevention. Improper timing of fuel 
pumps to the engine may be due to: 

(a) Failure to adjust pump properly. 

(b) Worn pump camshaft, 
(a) Failure to adjust pump properly. The timing pro- 
cedure differs somewhat for APE and APF pumps. - 

To time the APF pumps properly, it is necessary 
only to follow the timing instructions in the engine 
instruction manual. 

Instructions given in the engine instruction manual 
for timing the APE pump to the engine usually pre- 
suppose that the pump, which is actually a group of 
individual pumps, is properly internally timed. On this 
premise, it is necessary to time only one of the group 
of pumps to the engine. However, if the pump is not 
internally timed, that is, if the pumps are not timed 
with respect to one another, it will be impossible to 
time all pumps properly by timing only one of them. 
Specific instructions for internal timing of APE 
pumps will be found in the Bosch fuel injector main- 
tenance manual, obtainable from the Bureau of Ships. 

In timing either APE or APF pumps, the most 
serious error that can be made is the failure to provide 
sufficient clearance between the end of the plunger at 




maximum stroke and the delivery valve body. With 
APE pumps, it is possible to check for this clearance 
by inserting the point of a screwdriver between the 
tappet adjusting screw and the plunger when the 
plunger is at the highest position. The best check for 
plunger clearance of APF pumps is to bar the engine 
over carefully and observe whether or not the timing 
line on the plunger guide cup disappears from the 
inspection window in the pump housing. Never con- 
tinue to bar the engine when the line is not visible as 
this indicates insufficient clearance. Continued bar- 
ring will occasion severe damage to the pump, and 
possibly to other parts of the engine. 

The tappets should be tightened adequately, if they 
are used, so that they will not come loose and alter 

(b) Worn pump camshaft. If the cams driving the fuel 
pumps are worn, the timing will be influenced. With 
proper lubrication, little wear of the cams is experi- 
enced. In most cases, wear will be quite evident from 
the surface condition of the cams. If the camshaft is 
not too badly worn it will usually be possible to 
smooth up the surface with crocus cloth, or by careful 
stoning. No other abrasive should be used for this 
purpose. Generally it will be possible to retime the 
pumps without renewing the camshaft. However, 
when considerable wear is suspected, the cam dimen- 
sion can be checked against the engine drawings to 
determine the exact extent of wear. 

2. Repair. Instructions for proper timing of APF 
pumps to the engine are given in the engine instruc- 
tion manual. Generally, instructions for timing the 
APE pump unit to the engine are given in the engine 
instruction manual. However, internal timing and 
calibrating instructions may not be in that manual. 
Full instructions are given for timing and calibration 
of APE pumps in the Bosch fuel injector maintenance 

When it is necessary to retime a pump, it is probable 
that recalibration will also be advisable (see h. Pos- 
sible trouble: Pumps improperly calibrated (balanced), 
which follows). 

h. possible trouble: 
pumps improperly calibrated (balanced) 

Calibration, or balancing, of the fuel injection 
pumps is the process of adjusting each individual 
pump to deliver precisely the same quantity of fuel at 
a specific throttle setting. If some pumps are set to de- 
liver more fuel per stroke than others, the engine will 
be unbalanced, that is, some cylinders will carry a 

greater load than others. This may be detected by dif- 
ferences in cylinder exhaust temperatures and firing 
pressures, and by smoky exhaust from the overloaded 
cylinder. Roughness and engine vibration may also 
indicate unbalance of the fuel pumps. For APE pumps, 
the most conclusive test for improper calibration is the 
one performed on the American Bosch motor driven 
test stand. An emergency field procedure, not using 
this equipment, is also possible. Both of these methods 
are explained simply and concisely in the Bosch fuel 
injector maintenance manual. 

It should be remembered that many other engine 
difficulties may readily cause engine symptoms identi- 
cal to those due to unbalance. A few of the other 
faults that may be present and should be considered in- 
clude: poor condition of piston rings, inaccurate ex- 
haust pyrometer and thermocouples, mistimed injec- 
tion, and mistimed or faulty engine exhaust or inlet 
valves. Hence, it is apparent that the taking of exhaust 
temperature and combustion pressure readings is far 
from infallible as an indication of need for balancing 
the fuel injection pumps. 

1. Causes and prevention. Faulty calibration of fuel 
pumps is due to failure to follow instructions for cali- 
bration. Instructions for calibration of APF pumps are 
included in the manufacturer's instruction book. Cali- 
bration instructions for APE pumps are in the Bosch 
fuel injector maintenance manual. These instructions 
must be followed implicitly. 

2. Repair. To calibrate the pumps, follow the in- 
structions given in the maintenance manual. 

i. possible trouble: 


The plunger spring acts to return the plunger, after 
injection, to the bottom position of its stroke. The 
cylinder served by a pump with a broken plunger 
spring will fail to fire. 

1. Causes and prevention. Contributing factors to 
broken plunger springs are: 

(a) Failure to inspect springs thoroughly. 

(b) Careless handling of springs. 

(a) Failure to inspect springs thoroughly. Most broken 
springs develop from cracked springs. Cracks may be 
located in their incipient stages by careful inspection. 
Cracks will show up best if the springs are flexed 
during inspection. Pits or nicks also lead to failure. 
All questionable springs must be replaced to avoid 

(b) Careless handling of spring . When usi ng a cleani ng 

Digitized by tjOOQlC 

Origiral from 

fluid such M recommended piv pa^, 45, rasmclled 
springs, Of. other painted should not-is flowed 
to comt,^ c«aracrWith ^i; fluid. Thts ftutJ wilUl- 
most instafttancotisly caasc soften* rig and removal of 





,mi m^tal 5c|^mgS are n6c cnita 
Spnag* from which the wzimeiim been chipped or 
n ^houid be either touched up similar cornet, 
or refused. Sprtr,^ ruan t 5 ijt be mcked^aatched, df 

otherwise damaged "during '.overhaul;' i/K 1 V - 

2. K'tjm Ai l ^ 

igos of tacking, 

Figure 4-20 $b0vv S *iip»l<r in ptm in one type of WARNING WW* 
.no^lc holder: ; 

tfmm&zv be cl^Hkd :** ■«rfto:-ftifidc of. hole ^ ^ f & ^*»r„ ^ 

*A*/>U»#tti*. it it ititntisii riuxi all 

cion reaction, or wtbub^ within AX) {Sounds of (he «{\tuli<-d ruling prcsrar? i* 

Figure 4-20. Nozzle and nozzle holder. 




t ne v«u-ve sjipuia r>e inserted * u trie doo y n aac^uu te< y 
no^Je valve will slide K> its sear \n the 
narfcle body by tis ^fl weight If the mnzU: val ve «v 

cleaned by placing .a quantity of clean muuotl tulbw 
im the valve torn, and roeatmg u within the. body, 
fl^ / ,ippfttz ^mpuwtd ts not to he used for this cicam^ope^- 

^ 1 "f . valve and luidv in fuel -ail,- and the slide rest is re- 

to a rexronduian- 
ss tar this work 
pre ye n t ed fr om s lick i %g by 
1M |PP ro P a ' adjustment ot pressure- spring. making certain t'teu att foci used t.v proper) v- : glared 

(b) No^te valve stuck m boay. and cefttttftt^: Ati r^ies .steuid he cieaned rhor- 

(c) Clogged dozzk: orifices ouphly. vmh so-called carbon solvents, whenever they 
(a) improper adjustment of prtxttm spring. The opening do noe u > hc fuiKtioning properly : When m- 

prcssure of a proper I v periling nozzle is determined ^vfeu, care should be exercised to mtert 

by the compression -uf the pr^are^^^ that they arc pmpcrjy posiuoncd. . 

This adjasmicnr is accomplished either bv an ad-jutrlog WP'tftf.*®!' No ? zle anhces occasional^ 

- i , c , ^ n- become do$#ed with ' .^iw>-<b* ; -6a^d*fe. ■■; vXh'ts. .dot 

screw m by shuns. Figure, 4-22 dlusnates vanaaons ^ . . ^ , 

in mctnoa of adjustment ..tor 


To reduce trie mztic opening pressu 

body be reitiovcd from the holder and Allowed to soak aiJgk as that at which the .orifice is drilled . Failure 


The broker portion 


>n may then defy removal See the opening 1 :pre$mc, make the necessary adjustment, or 





D. possible trouble: 


This trouble is usually recognized in the same man- 
ner as ;. Possible trouble: opening pressure too 
high, pp. 51-54. That is, using a nozzle tester, the 
nozzle will be found to open at a pressure lower than 
that specified. 

1. Causes and prevention. Low nozzle opening pres- 
sure may be due to: 

(a) Improper adjustment of pressure spring. 

(b) Broken pressure adjustment spring. 

(a) Improper adjustment of pressure spring. (Sec a. Im- 
proper adjustment of pressure spring, page 53.) This refer- 
ence explains how to adjust the spring compression for 
lower opening pressure. To raise the nozzle opening 
pressure, the spring compression is increased by screw- 
ing down the adjusting screw or by adding shims. 

(b) Broken pressure adjustment spring. If the pressure 
adjustment spring is broken there will be no resistance 
to the opening of the nozzle valve. This will probably 
cause dribbling, rather than formation of a spray pat- 
tern at a lower pressure. The condition of the pressure 
adjustment spring should be checked. Any sign of 
cracking is cause for replacement of the spring. 

2. Repair. Generally, low opening pressure may be 
remedied by adjustment of the pressure regulating 
spring. Following adjustment, the spring adjustment 
retaining nut should be clamped securely to avoid 

c. possible trouble: 


This trouble may cause detonation and is also likely 
to cause crankcase dilution. It contributes to carbon 
formation on the nozzle and smoky exhaust. The 
nozzle should be checked for dribbling by attaching 
the nozzle and holder to a nozzle tester, such as shown 
in Figure 4-21, and depressing the pump handle. 
Dribbling (collection of drops of fuel at end of the 
nozzle) at a pressure lower than 200 pounds below the 
specified opening pressure, or after injection has oc- 
curred, is an indication that the nozzle is not operating 

1. Causes and prevention. Dribbling of nozzles may 
be due to: 

(a) Damaged valve or valve body scat. 

(b) Dirty nozzle. 

(c) Broken pressure adjusting spring or screw. 

(d) Nozzle valve stuck in nozzle body. 

(a) Damaged valve or valve body seat. The nozzle valve 
seat and the nozzle body seat should be inspected care- 
fully for pit marks, cracks, erosion, or other condi- 
tions that would interfere with proper seating. A bent 
nozzle valve may result in the valve hanging open, or 
partially open. When assembling a nozzle, a centering 
sleeve or thimble should be used to position the nozzle 
properly in the nozzle cap nut. Shim stock can be used 
if the thimble is not obtainable. 

Proper centering will reduce the probability of the 
valve or body warping when the nozzles and holder 
are installed in the engine, as nozzles may fit closely in 
the engine recesses. Care should be taken to clean the 
nozzle recesses in the engine to assure adequate heat 
transfer and to guard against cocking the valve body 
and binding. Protection of spray valves is provided by 
thorough filtration and centrifuging of all fuel. Water 
or dirt in the fuel will cause corrosion and erosion of 
valve seats and orifices. 

(b) Dirty noz$}e. Leaky nozzles are frequently due to 
the presence of dirt particles on the valve seating sur- 
faces. Nozzles should be protected by adequate filtra- 
tion and should be cleaned with some suitable solvent 
to remove any gum deposits. 

(c) Broken pressure adjusting spring or screw. Breakage 
of the pressure adjusting spring will allow the nozzle 
to dribble. Likewise, a broken or stripped pressure 
adjusting screw will cause dribbling. All parts should 
be inspected carefully whenever the nozzle and holder 
are overhauled, and replacement made of any parts 
showing cracks. Springs should be flexed when in- 
spected, as this will make cracks easier to locate. 

(d) Nozzle valve stuck in nozzle body. Sec b. Nozzh 
valve stuck in nozzle body y page 53. 

2. Repair. Leaking or dribbling nozzles may fre- 
quently be repaired and placed in service again. When 
a nozzle is found to be leaking, it should first be cleaned 
thoroughly by soaking overnight in a suitable solvent, 
followed by scraping off the incrustations with brass 
tools or tools made of a softer metal. The nozzle body 
should then be clamped in a vise with protected jaws, 
and the nozzle valve coated with clean mutton tallow 
and rotated into the valve body. Usually this will re- 
move the surface deposits responsible for leakage. 

In the event that this procedure does not prove effec- 
tive, the lapping process, explained in detail in the 
Bosch fuel injector maintenance manual, may be 
necessary. This is an extremely delicate operation, and 
unless all the safeguards enumerated in the Bosch 
manual are followed, the nozzle may be ruined. 

Any nozzle must be replaced if it is cracked, ex- 
tremely eroded or so badly stuck that removal is not 

Digitized by GO< .gle " 




large drops of fuel visible. "Streamers," or "flags," 
visible in the outer portion of the spray, as shown in 
Figure 4-25 B, indicate that the nozzle is not func- 
tioning properly. 

In checking hole type nozzles for spray pattern, the 
orifices should first be examined with a magnifying 
glass, counted, and an attempt made to visualize what 
the spray from the nozzle will look like if all the ori- 
fices are clear and delivering an equal quantity of fuel. 
The nozzle is then placed in the hand tester, a pumping 
speed of about 65 strokes per minute attained, and 
careful observation made of the nozzle spray pattern. 
Each orifice should deliver about the same quantity of 
fuel, and there should be no coarse drops in the pat- 
tern. Most, but not all, nozzles have a symmetrical 
pattern and the angles of delivery from the orifices are 
the same. If doubt still exists as to what the pattern 
should look like, the orifices should be recounted and 
their location again noted. 

1 . Causes and prevention. Distortion of the spray pat- 
tern is caused by : 

(a) Dirty nozzle orifices. 

(b) Eroded nozzle orifices. 

(c) Eroded nozzle valve. 

(d) Broken pintle. 

(a) Dirty nozzle orifice. Clogging of orifices with 
carbon, cleaning wires, or dirt from fuel will interfere 
with the proper flow of fuel. The fuel should be kept 
clean by adequate filtration, and the nozzles kept clean 
as specified under (c) Clogged nozzle orifices, page 53 

(b) Eroded nozzle orifices. Wear of orifices is generally 
the result of inadequate filtration or centrifuging of 
the fuel. Abrasive particles and water in fuel, if not 
removed, can result in this condition. 

(c) Eroded nozzle valve. Marring of the conical sur- 
faces of the nozzle valve by erosion can distort the fuel 
sprav pattern. The fuel must be kept clean and water 

(d) Broken pintle. Pintle type nozzles when handled 
should receive extra care to avoid damaging that por- 
tion of the nozzle valve which protrudes below the 
bottom of the valve body. In several instances, over- 
zealous operators, in attempting to scrape the nozzle 
body free of carbon with a pocket knife, have inadvert- 
ently removed the pintle. In other instances, pintles 
have been broken off by striking or dropping the nozzle 
and holder on a hard-surfaced bench. Only cleaning 
tools of brass or other soft material must be used. 
Pintle nozzles must be handled with extra care. 

2. Repair. Distortion of the spray pattern is usually 
due to dirt in the nozzle. If, after thoroughly cleaning 

Digitizes by G<X 

the nozzle, the spray is still distorted, it is probable 
that erosion of the valve or orifices has occurred. Such 
a condition requires replacement of the nozzle. A 
faulty nozzle should be used only in an emergency. 

e. possible trouble: 
nozzle fails to chatter 

When nozzles are tested on the hand operated test 
stand, most types, excluding the throttling type pintle 
nozzle, should emit an intermittent snapping noise, 
termed chatter, when the handle is slowly depressed. 
This chatter is caused by the rapid opening and closing 
of the nozzle valve. Frequently, a nozzle which fails 
to chatter will also leak or dribble. 

1. Causes and prevention. Failure of nozzles to chatter 
may indicate a sticky nozzle valve. If the nozzle chat- 
ters it signifies that the nozzle valve is capable of re- 
sponding readily to changes in pressure. Failure to 
chatter may indicate that the nozzle valve is not as free 
in the nozzle body as it should be. Binding may occur 
due to gummy deposits on the valve stem, distortion of 
the valve, or distortion of the valve body. Causes of 
distortion include: overtightening the nozzle cap nut 
or nozzle holder retainer, failure to use nozzle center- 
ing sleeve, and use of gasket between surface of engine 
and nozzle body when not specified by manufacturer. 

2. Repair. Repair of a sticky nozzle usually consists 
only of cleaning the nozzle thoroughly. Sec b. Nozzle 
valve stuck in nozzle body, page 53- A permanently dis- 
torted nozzle valve or body will require replacement 
of the nozzle. 

f. possible trouble: 
excessive overflow from nozzle 

leak-off connection 

As some slight leakage between the valve and valve 
body is desirable for lubrication, provision is usually 
made to carry off any leakage of this nature. When the 
engine is operating or when the nozzle is being tested, 
the amount of leakage from the leak-off connection 
should, for most nozzles, be imperceptible. Any 
greater flow of fuel from this connection is significant 
and is an indication of nozzle trouble. It is likely that 
the cylinder served by such a nozzle will misfire either 
at intervals or continuously. 

1. Causes and prevention. Excessive overflow from 
leak-off connection of the nozzle may be indicative of: 

(a) Insufficiently tightened cap nut. 

(b) Excessive clearance between valve and body. 

(c) Dirt particles between valve and body. 

Original from 


(d) Damaged flat lapped surface of body or 


(e) Bleeder screw not tightened. 

(a) Insufficiently tightened cap nut. Examination of 
Figure 4-20 will explain this cause. The cap nut should 
be tightened sufficiently but not excessively. 

(b) Excessive clearance between valve and body. In such 
cases the valve will appear to be loose in the body. 
Such nozzles must be replaced. 

(c) Dirt particles between valve and body. This condi- 
tion will cause leakage. Thorough cleaning of the 
nozzle (see b. Nozzle valve stuck in body, page 53) will 
usually remedy it. The filters must be kept functioning 

(d) Damaged fiat lapped surface of body or holder. This 
will cause symptoms identical with (*) as described 
above. If it is not possible to stop the excessive 
overflow by tightening the cap nut, damage to the flat 
lapped surfaces may allow leakage. Care in assembly 
to prevent dirt particles from entering the nozzle, and 
to prevent cocking of the nozzle, will help to prevent 
this condition. 

(c) Bleeder screw not tightened. In cases where the 
bleeder screw is situated as shown in Figure 4-20, ex- 
cessive overflow may be due to a faulty or untightcned 
bleeder screw. 

2. Repair. After determining the cause of leak-off, all 
loose parts must be tightened. Damaged flat-lapped sur- 
faces must be lapped as specified in the Bosch fuel injec- 
tor maintenance manual. All parts must be cleaned thor- 
oughly and replacement of parts made where necessary. 

g. possible trouble: 
nozzle turns blue after service in engine 

On rare occasions, the nozzle tip and/or the nozzle 
valve will turn blue. This condition is indicative of 

severe overheating and must not be allowed to con- 
tinue. Bluing should not be confused with corrosion 
or gum deposits on the nozzle body or valve. The blu- 
ing will be similar to that on metal firearm parts. 

1. Causes and prevention. Overheating of nozzle may 
be a result of: 

(a) Failure to clean nozzle recess properly. 

(b) Use of gasket when not specified. 

(c) Use of wrong nozzle in engine. 

(a) Failure to clean no^xle recess properly. After remov- 
ing the nozzle and holder from the engine, and before 
reinstalling the assembly, the nozzle recess should be 
cleaned thoroughly. Collection of scale on the surface 
adjacent to the nozzle will interfere with adequate 
transfer of heat and may be responsible for bluing of 
the nozzle. Attempts to insert the nozzle in an en- 
crusted recess may cause the body to be so distorted as 
to prevent free movement of the nozzle valve. 

(b) Use of gasket when not specified. A gasket should 
never be placed between the end of the nozzle and the 
engine nozzle recess surface unless the manufacturer of 
the engine definitely states that such a gasket be used. 
In an engine not designed to use such a gasket, it will 
interfere with the proper transfer of heat and may also 
cause nozzle distortion. In this connection, it is well 
to avoid tightening nozzle holders too tightly in the 
engine as this may also cause nozzle distortion. 

(c) Use of wrong nox&e in engine. It is entirely possible 
that some mistakes may have been made in the instal- 
lation of nozzles in an engine. A check should be made 
in the manufacturer's instruction manual and the 
Bosch fuel injector maintenance manual for the desig- 
nation of nozzles to be used in the engine. All cases of 
this nature should be reported to the Bureau of Ships. 

2. Repair. Blued nozzles indicate that they have 
been overheated and should be replaced at the earliest 

Tablb 4-a 



General Motors 

1. Positive displacement, lapped plunger and barrel type high-pressure 
pump. One pump per engine cylinder. Pump operated by cam. 
Plunger either single or double helix; barrel generally single ported. 

1. Positive displacement lapped plunger and bushing (barrel) type. 
One pump per engine cylinder. Pump operated by cam. Plunger 
usually double helix; bushing always double ported. 

2. Change in timing during operation accomplished either by rota- 
tion of pump camshaft with respect to engine drive shaft, or by 
rotation of pump plunger. 

2. Timing varied by rotation of pump plunger. 

3. Variation in quantity of fuel pumped per stroke accomplished 
by rotation of plunger. 

3. Variation in quantity of fuel pumped per stroke accomplished by 
rotation of plunger. 

4. Pressure actuated spray valve. Popping pressure adjustable. 

4. Pressure actuated spray valve. Popping pressure not adjustable. 

5. Spray nozzle almost universally separate from high-pressure 
pump; interconnected by high-pressure line. 

5. Spray nozzle and high-pressure pump in single unit; no high-pres- 
sure tubing required ; hence the name unit injector. 

6. Snray nozzle may be either orifice or pintle type. 

6. Multiple orifice type spray tip used universally. 

Digitizes by 

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f /9«re 4-28. Rector te*f 

Although, the fixture illustrated is Ixueaded pri- 

caded pri- 

tui-c sprav tip orifice test, vj|vc opening pressure 
i ■ijfjt-'A test: and holding pressure tot.- Complete details on 
test P r.<eJurc ate coatni.jed m the C M fuel injector 
now 9 cms of mw'ntenance manual 

iuiiilar tii those encountered with Bosch equipttjTOt :fuel ih.imtser tiirougtj riie other hid connection H'rhe 


the rack opening in the body, it is likely that the 
plunger and or bushing is damaged. It must not be 
forgotten, however, that rapid decline in pressure may 
also be indicative of poor condition of other lapped 

Visual inspection of plunger and bushing during 
overhaul of the injector may disclose scoring, pitting, 
erosion, or other damage. (See a. Possible trouble: Dam- 
aged plunger and barrel, page 45, for inspection 

1. Causes and prevention. Damage to plunger and 
bushing may occur through : 

(a) Entry of dirt into the pump. 

(b) Careless handling while disassembled. 

(c) Corrosion. 

(d) Disintegration of fuel filter. 

(a) Entry of dirt into pump. Dirt is responsible for 
practically all the trouble encountered with fuel injec- 
tion equipment. Proper maintenance of fuel filters and 
strainers will protect injectors while operating. Care 
in the selection of a proper, spotlessly clean working 
space is the first requisite for protection of injectors 
during overhaul. Ideally, an injector shop should be 
air conditioned. All air should be thoroughly filtered 
prior to entry into the enclosed space. Benches should 
have smooth tops. Metal topped benches should be 
covered with linoleum or hard fiberboard. The use of 
ample quantities of suitable cleaning solvent, clean 
fuel oil, and of compressed air to blow parts dry, will 
insure cleanliness during overhaul. Rags or waste 
should never be used to clean injectors as lint particles 
from them will damage injector parts. (See (jt) Entry of 
dirt into pump, page 46.) 

(b) Careless handling while disassembled. When several 
injectors are disassembled simultaneously, it is imper- 
ative that the lapped parts of one injector do not 
become interchanged with those of another injector. 
Plungers and barrels are fitted to one another and must 
not be replaced individually. In addition to this pre- 
caution, it is necessary that the precautions stated 
under (i) Careless handling while disassembled, page 46, 
be observed. 

(c) Corrosion. Rust, pits, or discoloration on plunger 
or bushing lapped surfaces may be due to water in the 
fuel, use of corrosive diesel fuel (unlikely if Navy 
standard fuel is used), or handling dry lapped surfaces 
with perspiring hands. The hands should always be 
washed in diesel fuel, and lapped parts dipped in clean 
fuel prior to handling them. 

(d) Disintegration of fuel filters. On some occasions, 
the sintered bronze fuel filters incorporated in the body 

Digitized by GQoQIC 

of some injector models have broken up and found 
their way into the pump, causing extensive damage to 
both plunger and bushing. The best insurance against 
such an occurrence is to change filters whenever the 
injector is serviced. Filters should not be removed, 
however, unless the injector is to be cleaned thor- 
oughly, as there is considerable danger of introducing 
dirt into the injector by disturbing the position of 
these filters. 

It is believed that disintegration of the filter is due 
to the presence of water in the diesel fuel. Careful 
centrifuging of all fuel used will prevent this. 

2. Repair. If the plunger or bushing is found to be 
scored, eroded, chipped, pitted, distorted, or other- 
wise damaged, both must be replaced. Neither may be 
replaced singly. When either is damaged, a new plunger 
and bushing assembly must be installed. 

b. possible trouble: 
external leakage from injectors 

This trouble becomes apparent during the holding 
pressure test described under a. Possible trouble: Damaged 
plunger and bushing, page 60. Prior to performing this 
test, care must be taken to wipe the injector dry, giv- 
ing particular attention to the spray tip. While the 
injector is under pressure its exterior should be thor- 
oughly scrutinized for indications of leakage. 

Leakage outside the combustion chamber consti- 
tutes a fire hazard, while leakage from the tips of the 
injectors may cause smoky operation, crankcase dilu- 
tion, or misfiring of the cylinder served by this injector. 

1. Causes and preventions. Leakage from the injector 
is usually due to: 

(a) Loose connections. 

(b) Faulty gaskets. 

(c) Damaged threads. 

(d) Damaged sealing surfaces. 

(e) Broken valve spring. 

(a) Loose connections. When leakage is observed, a 
check should be made of all threaded members to 
ascertain whether or not they are tight. 

(b) Faulty gaskets. Leakage from the injector may 
occur as a result of damage to a gasket. Gaskets should 
be replaced every time the injector is disassembled. 
Care must be taken to see that the gaskets, or seal 
rings, are properly positioned prior to tightening 
the parts. 

If it is necessary to re-use a copper gasket, it should 
be softened, or annealed, by heating it to a dull red 
color and quenching it in water, prior to reinstallation. 

(c) Damaged threads. When inspecting parts, partic- 

Qrigiral from 



ing, only slight distortion of cither is necessary to 
cause binding. Distortion may result from dropping or 
striking the plunger or bushing on the deck or other 
hard metal surfaces. Great care should be exercised in 
handling the plunger and bushing and all other lapped 
parts of the injector. It is advisable to select a bench 
with a smooth wooden top, or to cover a metal bench 
with linoleum or hard fiberboard, if much fuel injector 
work is contemplated. The work should be done well 
over the center of the bench so that if parts are dropped 
they will not fall on the deck. 

2. Repair. Sometimes it is possible to free a stuck 
plunger by soaking the plunger and bushing in a car- 
bon and lacquer removing solvent, obtainable from the 
supply officer under the following stock numbers in 
the Standard Stock Catalog: 

Carbon and lacquer removing compound 

51C-1 567-56 5-gal can 

51C-1567-58 55-gal drum 

The plunger and bushing should soak overnight, or 
longer if necessary. These cleaning fluids will imme- 
diately soften and begin to remove any paint or enamel 
with which they come in contact. Likewise, rubber 
gaskets will be damaged by these fluids. If, after the 
plunger and bushing have been separated, it is found 
that the plunger does not slide freely within the bush- 
ing, it is advisable to clean the plunger and bushing 
further. The plunger should fall slowly but smoothly 
through the bushing by its own weight, and it should 
be possible to spin the plunger in the bushing by hand 
when the bushing is held in a horizontal position. 
This is accomplished by placing a small quantity of 
mutton tallow, or fuel oil and talcum powder mixture, 
on the plunger and working the plunger back and forth 
and around in the bushing to remove gummy deposits. 
Particularly obstinate stains on plungers may be re- 
moved by use of a limited quantity of jewelers' rouge 
on a piece of soft tissue paper. Cleaning tools for this 
process are described in the G.M. fuel injector main- 
tenance manual. 

It is important to remember not to lap the plunger 
to the bushing with abrasive such as jewelers' rouge. 
After cleaning the plunger with jewelers' rouge on tis- 
sue paper, the plunger must be cleaned thoroughly 
with diesel fuel before placing it in the bushing. If, 
after repeated thorough cleanings, the bushing and 
plunger still do not fit properly, it is probable that one 
or the other is distorted. In such cases it is necessary 
to replace the plunger bushing assembly. As plungers 
and bushings arc mated parts, it is not possible to re- 
place only a plunger or only a bushing. 

Digitized by GQoQIC 

d. possible trouble: 
rack sticking or jammed 

The rack, which controls the quantity of fuel in- 
jected per stroke, must be completely free. Stickiness 
of the rack, that is, resistance to motion, will result in 
governing difficulties. Hunting, or rising and falling 
of the engine speed at constant throttle setting, may 
be caused by such a condition. If the rack becomes 
jammed, it may be impossible to control the engine 
speed with the throttle. The rack may be checked for 
freedom of motion by disconnecting the governor link- 
age and attempting to move the rack by hand. There 
should be no resistance to movement of the rack when 
all springs and linkages are disconnected. 

If the injector is out of the engine, the rack freeness 
test should be performed. The rack is considered satis- 
factory if it falls freely, through its entire length, by 
its own weight when the injector is tilted from side 
to side. 

1. Causes and prevention. Stickiness or jamming of 
rack may occur as a result of: 

(a) Plunger stuck in bushing. 

(b) Dirt in rack mechanism. 

(c) Damaged rack or gear. 

(d) Improper assembly of pump. 

(a) Plunger stuck in bushing. If the plunger will not 
move up and down in its bushing, it may also fail to 
rotate. Since the linkage of each pump ties to a com- 
mon shaft that is connected to the engine governor, 
sticking of one pump plunger will, in some engines, 
prevent movement of the racks of all the other pumps. 
In other engines, a slip joint is provided at each rack to 
permit one rack to stick without affecting the other 
injectors (see c. Possible trouble: Plunger stuck in bushings 
page 62). 

(b) Dirt in rack mechanism. Dirt or metal particles 
between the teeth of the rack and gear can interfere 
with freedom of motion of the rack. Dirt must not be 
allowed to enter into the mechanism. 

(c) Damaged rack or gear. Through improper assem- 
bly technique, such as forcing parts together, it is pos- 
sible to damage the teeth of the rack or the gear. 
Burred, nicked, or bent teeth will prevent proper func- 
tioning of the rack and the gear. The rack should be 
examined carefully for straightness. 

(d) Improper assembly of pump. The rack and gear 
have matching marks to aid the operator in assembling 
them properly. Disregard of these marks may result 
in an assembly error severe enough to cause sticking or 
jamming of the rack. 

Original from 


2. Repair. The cause of sticking should be deter- 
mined, and any defective parts replaced. All parts 
must be cleaned thoroughly before reassembly. Errors 
will be avoided by careful study of the assembly 

e. possible trouble: 
backlash, or looseness, of rack 

This condition permits motion of the rack without 
a corresponding rotation of the plunger. As effective 
governing is based on the premise that for every 
change in engine speed there is a corresponding change 
in the fuel quantity injected per stroke, it is apparent 
that governing will be interfered with if backlash 
exists. Shimmy, or vibration of the rack while the 
engine is operating, may indicate such a condition. 
Speed variations are also indicative of this difficulty. 
Although these symptoms may be attributed to loose- 
ness of the rack, it should be remembered that malad- 
justment of, or dirty condition of, the governor may 
present similar symptoms. 

1. Causes and prevention. Backlash, looseness, or play 
in racks is generally due to: 

(a) Worn gear. 

(b) Worn rack. 

(a) Worn gear. When the injector is disassembled for 
overhaul, the gear teeth should be inspected for signs 
of excessive wear. W T ear in most cases is brought about 
by a dirty condition of the engine. Any governor con- 
dition that induces vibration of the rack, either inter- 
mittent or continuous, will, of course, hasten wear. 

(b) Worn rack. The sturdy construction of the rack 
and its relative hardness, as compared with the gear, 
makes it far less subject to wear than the gear. Rarely 
does wear of the rack occur. If it does occur, it is prob- 
ably due to an extremely dirty rack mechanism. 

2. Repair. If it is possible to move the rack more 
than .015-inch without moving the plunger, replace- 
ment of gear and/or rack is necessary. 

f. possible trouble: 
broken plunger spring 

As the injector is dependent upon the plunger spring 
to return the plunger to the top of the stroke after in- 
jection has occurred, breakage of this spring will pre- 
vent the injector from operating. Since the injectors 
are quite accessible in most engines, it is easy to locate 
a faulty injector. 

1. Cause and prevention. Breakage of plunger springs 
is due to: 

(a) Failure to inspect springs thoroughly. Whenever the 
injector is disassembled for cleaning or overhaul, the 
plunger spring should be inspected carefully for signs 
of nicks, pits, cracks, or excessive wear. By bending 
the springs while inspecting them, it may be possible 
to locate incipient cracks that are not otherwise ap- 
parent. Although inspection jobs may appear tedious, 
replacement of failed parts is equally tedious and time 
consuming. Time spent in inspection usually pays 
great dividends by eliminating many hours of repair 
work that might have been necessary if the inspection 
had not been thorough. 

2. Repair. Broken plunger springs must be replaced. 
If, during an inspection, the spring is found to be in a 
doubtful condition, it should always be replaced. 

G. possible trouble: 


This trouble becomes apparent when the injector is 
subjected to the spray tip orifice test as described in the 
G.M. fuel injector maintenance manual. This test is 
performed by filling the fuel chamber with clean diesel 
fuel, vigorously depressing the plunger follower, 
about 60 strokes per minute, by means of the popping 
lever on the test fixture, and observing the resultant 
spray pattern. It may also be recognized by collection 
of fuel drops around the spray tip when the injector is 
subjected to the holding pressure test (see a. Possible 
trouble: Damaged plunger and bushing, page 60), or the 
valve opening pressure test (see /. Possible trouble: Pop 
pressure too high, page 65). Dribbling may result in 
smoky operation, detonation, loss of power, crank- 
case dilution, and excessive carbon formation on spray 
tips and other surfaces of the combustion chamber. 

1. Causes and prevention. See (</) Damaged sealing 
surfaces, and (e) Broken valve springs, page 62. 

2. Repair. See 2. Repair, page 62. 

h. possible trouble: 
distorted spray pattern 

Although this trouble, over a period of time, will 
affect engine operation adversely, it is best recognized 
by subjecting the injector to the spray tip orifice test (see 
g. Possible trouble: Dribbling from spray tips, above). Prior 
to testing a nozzle for spray pattern, the number of 
orifices in the tip should be counted carefully. It will 
be helpful to use a magnifying glass for this inspection, 
as the orifices generally are quite minute. 

Each orifice should emit the same quantity of fuel, 
and the spray pattern should appear to be symmetrical 

Digitized by tjOOQlC 

Origiral from 


in all respects. Any diversion from a symmetrical pat- 
tern indicates need for repair. Distortion of the spray 
pattern will inhibit efficient combustion, and cause 
local deposits of carbon in the combustion chamber, 
smoky operation, and a general lowered efficiency of 
the engine. 

1. Causes and prevention. The causes of a distorted 
spray pattern are: 

(a) Clogged spray tip orifices. 

(b) Eroded spray tip orifices. 

(a) Clogged spray tip orifices. When it is noted that 
one or more orifices appears not to be discharging 
fuel, these orifices should be inspected carefully. In 
most cases, they will be found to be clogged with car- 
bon. However, if an attempt has been made to clean 
them, it is entirely possible that a cleaning wire may 
have been broken off in the orifice. Gradual clogging 
of spray tip orifices with carbon and gummy deposits 
is to be expected over a period of time. Extremely 
rapid clogging of spray tip orifices may indicate some 
abnormal engine condition such as worn rings, worn 
liners, or any condition that would be responsible for 
oil pumping or a reduction in the quantity of air taken 
into the cylinder. The use of additive type lubricating 
oil materially reduces such deposits. Clogging result- 
ing from broken wires can best be prevented by work- 
ing the cleaning wire into the orifice gradually and 

(b) Eroded spray tip orifices. Some erosion is to be 
expected. However, extremely rapid or severe erosion 
is usually the result of water or an abundance of abra- 
sive material in the fuel oil. These conditions can be 
forestalled by adequate filtration and thorough cen- 
trifuging of all fuel oil. 

2. Repair. Distortion of the spray pattern frequently 
may be corrected by removal of deposits from spray tip 
orifices. This may be accomplished most expeditiously 
by soaking the spray tip overnight in some such sol- 
vent as recommended under 2. Repair, page 63- After 
soaking, it is generally possible to push out the clog- 
ging substances, with little difficulty, by means of a 
cleaning wire held in a pin vise. Carbon deposits in 
the main fuel passage may be removed with a drill 
held in the hand vise. To avoid breaking off the clean- 
ing wire in the spray orifice, the operator should 
ascertain, prior to the cleaning operation, the correct 
size of wire and drill to be used for his particular spray 
tip. Specifications as to size of cleaning wire and drill 
for every type of G.M. injector arc given in the G.M. 
fuel injector maintenance manual. When using a 
cleaning wire or drill, care should be taken to insert it 

Digitizes by GOOJZlC 

in line with the hole. Inserting the wire at an angle 
different from that of the hole almost always results in 
breakage. There is no known method of repair for 
eroded spray tip orifices. Such tips must be replaced. 

i. possible trouble: 


By means of the test fixture shown in Figure 4-28, it 
is possible to determine the pressure at which the in- 
jector will pop; that is, the pressure at which the injec- 
tor valve opens. 

Injectors equipped with needle valve assemblies cannot be 
tested for opening pressure without special equipment. At- 
tempts to do so will result in severe damage to the test 
equipment and injector. Complete instructions for 
testing this type of injector are given in the G.M. fuel 
injector maintenance manual. The valve opening pressure 
test is similar to the holding pressure test (see a. Possi- 
ble trouble: Damaged plunger and bushing, page 60), 
except that the pressure of the fuel within the fuel 
chamber is increased until the injector pops, or sprays, 
fuel from the orifices. The pressure at which popping 
occurs is referred to as the pop pressure. When pop pres- 
sure is considerably above normal, as specified in the 
G.M. fuel injector maintenance manual, or when the 
injector will not pop, the injector cannot be expected 
to perform satisfactorily in the engine. 

1. Cause and prevention. When it is possible to build 
up a pressure considerably higher than the pop pres- 
sure of the injector, it is likely that this condition 
is due to: 

(a) Improper assembly of injector parts. In certain 
models of the G.M. injector, it is possible to reverse 
one of the check valves. This will cause the check 
valve to seat when fuel tends to flow from the injector 
to the engine. When installing a check valve, be ex- 
tremely careful to position it properly. 

2. Repair. If an injector is operated when its pop- 
ping pressure is excessive, serious damage may be 
inflicted upon the injector. Therefore, check valves 
must be assembled properly. The testing of a needle 
valve type injector for pop pressure should never be 
attempted unless special equipment is available, as 
otherwise it will be possible to build up extreme pres- 
sures without opening the needle valve. 

j. possible trouble: 
pop pressure too low 

This trouble is recognized in a manner similar to 
/. Possible trouble: Pop pressure too high, above. A pop 
pressure lower than that specified for the particular 

Origiral frcrn 


injector indicates that this injector would not func- 
tion satisfactorily in the engine. These values are 
explained in the G.M. fuel injector maintenance 

1. Causes and prevention. Subnormal pop pressure 
may be due to: 

(a) Weak valve spring. 

(b) Dirty sealing surfaces. 

(a) Weak valve spring. As the pressure at which the 
spray valve opens depends upon the stiffness of the 
valve spring, any condition which would tend to 
weaken the spring will lower the injection, or pop, 
pressure. Valve springs may become weak through 
fatigue, wear, or corrosion. Inspection of springs will 
usually disclose evidences of corrosion or excessive 
wear, if present. The length of the old spring may be 
compared with that of a new valve spring. If there is 
any noticeable difference in length, the old spring 
should be discarded. 

Corrosion may be minimized by proper storage of 
the injector when it is not in use in the engine, and by 
maintaining the diesel fuel in a water-free condition. 

(b) Dirty sealing surfaces. If any of the sealing sur- 
faces (see Figure 4-29), are dirty or damaged, the pop 
pressure may be subnormal. Clean all surfaces thor- 
oughly and lap them, where necessary, in accordance 
with instructions in the G.M. fuel injector main- 
tenance manual. 

2. Repair. When the injector is found to have a low 
pop pressure, it is advisable to clean all parts thor- 
oughly, replace the valve spring, and then retest the 
injector. Unlike the Bosch system, the G.M. system 
docs not permit adjustment of the valve spring 

k. possible trouble: 
injectors not balanced 

When this trouble exists, there is an inequality in 
the quantity of fuel injected into each of the cylinders. 
This trouble is also referred to as improper position of 
control racks, or faulty calibration. Symptoms associated 
with this trouble include: loss of power, smoky ex- 
haust, vibration, detonation, and uneven engine oper- 
ation. It is not possible to obtain maximum efficiency 
of the engine under such conditions. 

1. Causes and prevention. Unbalance of injectors may 
be due to: 

(a) Failure to follow instruction for setting 
control racks. 

(b) Improper assembly of injector. 

Digitizes by GOuQIC 

(a) Failure to follow instruction for setting control rack. 
The engine instruction manual contains complete in- 
structions for proper positioning of the fuel control 
racks. When this adjustment is made, the maximum 
amount of fuel will be injected by each of the injectors 
when one of the racks is all the way in; no fuel will be 
injected when one of the racks is all the way out. The 
conventional method of adjustment for most models is 
to adjust all the racks until they extend from the in- 
jectors a specified distance. This is a critical adjust- 
ment and should be made most carefully. 

(b) Improper assembly of injector. Due to the method 
used for balancing the injectors, it is essential that 
comparative rack settings between injectors correspond 
to comparative rates of fuel injection. If the matching 
marks on the rack and gear are disregarded, it is 
entirely possible to assemble the injector so that bal- 
ancing by the conventional method is impossible. The 
instructions for overhaul should be studied carefully 
before attempting the disassembly or assembly of an 

2. Repair. Improper balancing of the injectors may 
be remedied by making rack settings as specified in the 
engine instruction manual. Balancing, however, is 
not possible unless the injectors are assembled as they 
were designed to be. 

l. possible trouble: 
injectors improperly timed 

Mistiming of several injectors will result in uneven 
operation or vibration of the engine. Early timing 
generally results in detonation, whereas late timing 
results in smoky exhaust, high exhaust temperatures, 
lowered firing pressure, and loss of power. 

1. Causes and prevention. Mistiming of injectors is 
due to: 

(a) Failure to follow instructions for timing. 

(b) Loose adjusting screw. 

(a) Failure to follow instructions for timing. The engine 
instruction manual contains information as to how to 
time injectors to the engine. Each injector is driven 
by a cam through a rocker arm, and in some engines, a 
push rod. Correct timing necessitates that the plunger 
of each injector, when that injector is not depressed, 
that is, when the rocker arm or push rod is on the base 
circle of cam, be in the same relative position with re- 
spect to the ports. Furthermore, each plunger must be 
a certain specific distance from the port. Timing is 
simply accomplished, in most cases, by use of a timing 
tool which serves as a guide to position the injector 
plungers properly. 

Qrigiral from 

care should he taken .to -sec that the adjustment screw given in the mstructicm manual, 
lock nut is pronerfv secured Loosenine wiJi change 

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a. possible trouble: 
pump unbalanced 

The fuel injection system is considered to be unbal- 
anced when unequal volumes of fuel are being injected 
into the engine cylinders. This is evidenced by uneven 
engine operation. 

1. Causes and prevention. Causes of an unbalanced 
pump are as follows: 

(a) Worn plungers and cylinders. 

(b) Scored plungers and cylinders. 

(c) Faulty check valves. 

(d) Faulty nozzles. 

(e) Sticking plungers. 

(a) Worn plungers and cylinders. When the parts of 
the hydraulic unit become worn, the rates of leakage 
increase. It is impossible to control the rate of leakage 
and it is also impossible to increase the effective stroke 
of an individual cylinder, inasmuch as there is no 
mechanical provision for doing so. Some allowance 
for unequal fuel delivery can be made by rearranging 
the discharge check valves. 

The effect of leakage is most noticeable at low 
speeds and does not become apparent at operating 
speeds until the wear is excessive. 

The greatest cause of wear is contaminated fuel. 
Existing filters are capable of removing particles suffi- 
ciently large to score the plungers and cylinder bores. 

(b) Scored plungers and cylinders. This subject is cov- 
ered in b. Possible trouble: Scored plungers and cylinders, 
page 70. 

(c) Faulty check valves. Faulty check valves can cause 
irregular and unequal pump discharge. The check 
valve can be disassembled for inspection. However, 
the ball check and valve seat cannot be lapped satis- 
factorily; if they are defective, they must be replaced. 

(d) Faulty nozzles. Improperly adjusted injector 
nozzles will cause unequal fuel distribution. The pop- 
ping pressure of the pressure actuated nozzles has a 
direct bearing on the quantity of fuel delivered. An 
increase in nozzle opening pressure usually results in a 
decrease in the quantity of fuel injected. 

Dirty, clogged, and sticking nozzle valves will also 
cause erratic engine performance (see a. Possible 
trouble: Faulty injection nobles, page 72). 

(e) Sticking plungers. On the delivery stroke, the 
plungers are actuated by the shoe plate which rides on 
the swash plate. On the suction stroke, however, the 
plungers are actuated by the plunger return springs. 
When the plungers become scored, or coated with a 
fine layer of resinous gum, they tend to stick and will 

Digitize by G<X 

not return. This condition necessitates the complete 
disassembly of the hydraulic unit as outlined under 
2. Repair, page 71. 

2. Repair. When aboard ship and away from a repair 
ship, it is advisable merely to replace the hydraulic 
unit. No attempt should be made to balance the fuel 
injection system unless a calibrating machine is avail- 
able. There are not many calibrating machines made 
specifically for the Excello pump; however, it is rea- 
sonably easy to adapt a Bosch test stand to accommo- 
date the Excello pump. Illustrations of this conversion 
are given in the Excello Fuel Injection Equipment Main- 
tenance Manual, NavShips 341-5026. A copy of this 
publication should be obtained by every ship, repair 
base or school handling Excello equipment. 

When replacing the hydraulic unit, injection nozzles 
should be removed and inspected. The popping pres- 
sures should be checked to make sure that they con- 
form with the pressures specified in the instruction 
manual for the particular engine. 

If a test stand with suitable adapters is available, the 
entire fuel pump is installed in the stand and the neces- 
sary shaft and fuel line connections are made. Each 
discharge check valve is connected to a properly cali- 
brated injection nozzle. It will be necessary to discon- 
nect the throttle control linkage and to provide some 
means of keeping the throttle control lever in the full 
throttle position while testing. When testing the 
pump, the test stand is run at about 300 rpm with the 
pump throttle set at the full throttle position until one 
of the graduated cylinders becomes full. The volume 
of fuel discharged from each nozzle is then recorded. 

The above test is repeated at a speed of about 
600 rpm and the readings again recorded. The varia- 
tions of readings taken at 300 rpm and 600 rpm are 
compared. It is expected that the variation will be 
greater at the lower speed due to the greater effect of 
leakage at the lower speeds. 

If, at the higher speed, the maximum variation is 
within 10 percent of the maximum volume discharged, 
the pump is considered to be satisfactory. Variations 
up to 25 percent at the lower speed are acceptable. 

If the variation is greater than that specified above, 
it may be possible to make some correction for the 
discrepancy by interchanging the delivery check 
valves. This is done by interchanging the delivery 
check valve from the pump cylinder having the maxi- 
mum discharge with that from the cylinder having the 
minimum discharge. 

After interchanging the check valves, the pump 
must be tested again. By careful and patient changing 

Original from 


of the discharge valves, it is often possible to calibrate 
the pump within the acceptable limits. 

b. possible trouble: 
scored plungers and cylinders 

The first indication of a scored plunger and cylinder 
bore will be uneven engine operation at low speeds. 
Trouble will be experienced when idling the engine, 
and it will be necessary to increase the idling speed to 
prevent excessive roll and stalling. As the scoring 
becomes worse, increased difficulty will be experienced 
in preventing the engine from stalling. A scored 
plunger and barrel will allow fuel oil leakage and will 
result in less fuel oil being delivered to the engine 
cylinder affected. 

Other fuel system defects such as faulty nozzle, 
check valve, leaking high-pressure fuel lines, etc., may 
cause the same symptoms. 

1. Causes and prevention. A scored plunger and barrel 
can be attributed to one of the following: 

(a) Dirt in the fuel oil. 

(b) Water in the fuel oil. 

(c) Careless assembly. 

(a) Dirt in the fuel oil. One of the greatest difficulties 
encountered in the jerk pump type of fuel injection 
equipment is that of keeping the fuel free of all 
abrasives. Every precaution has been taken by the 
manufacturer to provide means for the removal, before 
they reach the plungers and barrels, of any foreign 
particles that may enter the system. To accomplish 
this, the manufacturer has specified that every system 
be equipped with a strainer and filter in addition to 
the safety filter mounted directly on the pump. If the 
strainers and filters are properly maintained and arc 
serviced regularly, little trouble should be encountered. 

The filters and strainers should be serviced as out- 
lined on pages 92-97. It is necessary to drain the pri- 
mary strainer daily to remove the major part of the 
water and sediment. 

The plungers in the hydraulic unit are lapped to the 
cylinder bores. The clearances between the plungers 
and bores are extremely small, and are incapable of 
accommodating any foreign material. When foreign 
particles do get into the hydraulic unit, the usual re- 
sult is scoring and permanent damage to the entire 
hydraulic unit. 

Inasmuch as the cylinder bores are all cast together, 
the scoring of one cylinder necessitates replacement of 
the entire assembly. Each plunger is individually 
lapped and fitted to a specific bore, and one plunger is 
not interchangeable with another, even in the same 

Digitized by GOuQIC 

(b) Water in the fuel oil. Water, like dirt, will cause 
pitting and scoring of the finely finished plungers and 
cylinder bores. Water should be trapped in the pri- 
mary strainer. The strainer should be drained daily to 
remove any accumulation of water. 

(c) Careless assembly. Many Excello pumps are dam- 
aged permanently during overhaul or inspection. Every 
precaution must be exerted to insure that the surfaces 
of the plungers and the cylinder bores are not damaged. 
In handling the hydraulic unit, precautions and prac- 
tices listed under 2. Repair, page 71, must be followed 

2. Repair. Seriously scored plungers and cylinder 
bores cannot be repaired. Slight abrasions may be 
relieved, however, by lapping the plunger and bore as 
outlined under 2. Repair, page 71. 

If serious scoring is evident, it will be necessary to 
replace the entire hydraulic unit. 

c. possible trouble: 


Occasionally, the plungers in the hydraulic unit will 
stick in the cylinder bores. The plungers may remain 
stuck until disassembled, or the sticking may be only 
intermittent. A stuck plunger causes the engine to 
misfire on the affected cylinder and usually is accom- 
panied by a metallic noise within the pump. 

1. Causes and preventions. Sticking plungers may be 
caused by : 

(a) Gum deposits. 

(b) Foreign particles. 

(c) Broken return spring. 

(a) Gum deposits. The chief cause of sticking plungers 
is resinous gum deposits from the fuel oil. This condi- 
tion usually occurs after the engine has been idle for a 
long period. The removal of these deposits requires 
complete disassembly of the hydraulic unit as outlined 
under 2. Repair, page 71. The plunger should then be 
given a thin coat of mutton tallow and worked back 
and forth in the bore. If this does not tend to 
eliminate the binding, it may be necessary to lap the 
plunger and bore with a small amount of jewelers' 

(b) Foreign particles. Plunger to cylinder bore clear- 
ances do not allow for any foreign particles. When 
such particles enter the cylinder, they cause scoring 
and galling of the finely lapped surfaces and conse- 
quently, in many cases, cause the plungers to become 

(c) Broken return spring. A broken or weak return 
spring may cause the plunger to stick and not return 

Qrigiral from 


on its suction stroke. Whenever the hydraulic unit is 
disassembled, the return springs should be inspected. 

2. Repair. When the plungers are caused to stick by 
gum deposits or by abrasives, the unit should be re- 
moved from the pump body and completely dis- 
assembled. The procedure and precautions briefed 
below must be followed. 

(a) The work should be done only on a clean bench 
from which all objects not actually needed for dis- 
assembly or reassembly of the unit, have been removed. 
The bench should be wiped with fuel oil, and then 
wiped dry with a clean cloth. 

(b) Three or four shallow pans or glass dishes must 
be obtained, and each filled about one-quarter full with 
clean fuel oil. 

(c) The unit is disassembled, starting with the check 
valves. The name plate is removed, and the setscrew 
beneath it is withdrawn to release the throttle shaft 
assembly. When the throttle shaft assembly has been 
removed, the rotor and the control collar can be with- 
drawn. The spring case is next removed, and then the 
plungers. A check should be made on each plunger as 
it is removed to see that the number on the plunger 
corresponds with the number on the cylinder. All 
parts should be set in the fuel oil pans as they are re- 
moved from the unit. 

(d) Each part is rinsed and then placed on paper 
toweling to drain. 

(e) Each plunger must be checked individually in 
the bore to which it belongs; the plungers must not be 
interchanged. If a plunger tends to stick, or in any 
manner bind within the bore, a slight amount of mut- 
ton tallow should first be applied to the plunger, and 
then the plunger should be worked back and forth 
several times with a rotating motion. If this does not 
alleviate the trouble, it will be necessary to repeat the 
above procedure using a small amount of jewelers' 
rouge. In the event that jewelers' rouge is not avail- 
able, satisfactory results may be obtained by using a 
small amount of talcum powder mixed with a drop or 
two of fuel oil. Nothing coarser than talcum powder 
must ever be used when lapping the plungers and 
cylinder bores. Aft^r lapping the plunger and bores, 
the parts must be washed free of all traces of the rouge 
or talcum powder, and the plunger again tested in the 
bore. In some cases, it may be necessary to repeat this 
procedure several times before satisfactory results are 

(f) The hydraulic unit is reassembled and installed 
on the pump. 

(g) The calibration of the pump must now be 
checked. The procedure for this can be found under 

2. Repair, page 69. Repair and maintenance methods 
are fully discussed in the Excello fuel injector main- 
tenance manual. 

d. possible trouble: 
system air bound 

Hard starting, or failure to start, may be caused by 
the fuel pump becoming air bound. 

To facilitate starting, the system should be bled 
whenever any part of the pump has been disassembled. 
It is advisable also to bleed the system whenever the 
engine has remained idle. 

1. Causes and prevention. A pump may become air 
bound due to: 

(a) Loose connections. 

(b) Insufficient fuel. 

(a) Loose connections. Improperly tightened connec- 
tions on the suction side of the transfer pump will 
cause air to become trapped in the system. All fuel 
lines on the suction side of the pump must be inspected 

Loose connections beyond the pump will cause fuel 
leakage during operation, and also when the pump is 
idle. When idle, the fuel within the pumps and safety 
filter will be displaced by air. 

(b) Insufficient fuel. The pump will become air bound 
each time the fuel runs out, and the pumps must be 
bled before again attempting to start the engine. 

2. Repair. The pump is bled by the use of the hand 
priming pump and by loosening the bleeder screw at 
the top of the safety filter. 

4G2. Excello fuel injection nozzle. The Excello 
injection nozzle is of the pressure actuated type. It 
embodies a wire mesh fuel strainer and a spring loaded 
pintle valve. The nozzle is a factory calibrated and 
sealed assembly. No provision is made for adjustment 
of the nozzle opening pressure. 

a. possible trouble: 
faulty injection nozzles 

Faulty nozzle operation is evidenced by smoky ex- 
haust, detonation, uneven engine operation, and exces- 
sive carbon deposits within the engine cylinder. 

1. Causes and prevention. Faulty nozzle operation 
may be caused by one or more of the following: 

(a) Improper opening pressure. 

(b) Scored pintle valve or valve seat. 

(c) Sticking valve. 

(a) Improper opening pressure. The pressure at which 
an injection nozzle opens greatly affects engine opera- 
tion. Nozzle opening pressures for the nozzles used in 

Digitized by «Ole " ^ 


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ln<ims$e<nbim the mwJe, it i*6r$c. removed^ 
the teUer i.p.,i 'cleaned ol j 1 i esfenor carbon deposits 
'dec ot tot tor wircttl or 14 tr.ttfe^ is nLieed in the 

of the plate should nor he ativmpttd hv fwog it with 
, knife or Hmiiac rtul With the plat* remold, rtic 
nicer can be removed readily. I* eta lUMtk or guide 
cup is etmk. ihe of the unit should be 
soaked, in wrboti and lacquer fyrsoying 1 , compound ' 
" j . Fo.i ><J >r<> c i-. Cai No. SiO'J567 -56), This wiii 
. f tend fo looser! the d epos i cs suffic tent lv to uiJu.w dis- ci the valve and .up. The removal of 
the vii.h-c apd- guide cup. ss; atci.'nipJjshed by the use 
ofa special strand ami rc<w»\»'ig cool .. lC Figured). 

ft*** f«.%fW,W.^ n o^ A^tosem^ the pares -aiu.t be cleaned t^- 

DJcte- Go ale " 72 

then iKsptcrc 
use of i m 
ate checked for ea 


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g f the nozzle iui4*«alvc must ta-- rinsed For compile information and instructions on the 
vi th clean Aid oil maintenance procedures, refer to the Excdlo fuel injec- 

»#&eguUtecyp»ikl rh«-sprfns scfrtaccS' ' cot maintenance manual. 

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securing cover to the distributor housing must be 
Nu^ed otf cvcnlv in such a manner chrtt :<u even spring 

"mhivcor disk fern catching in its bu$bmg.^nd scoring. 
rh«? w>uin£ surfaces. This spring pressure, is m*U0~ 
tained by the distributor disk spring which serves? to 
'h.oJd-rhc d is cr&uiUr cover and disk together eighth- 
and thus prevent fuel leakage; The recommended pro- 
cedure for removal of the cap screws is to remove 
every other one, then loosen the three remaining cap 
"crews one-half turn, at a ririiO: This procedure* mavn- 
aim the even pressure required. 

asu.dues have iKOitrcd as the result of 


fuel through the distributor will be disrupted after the 
engine is started. 

(c) Inoperative gear pumps. Any failure of the gear 
pump to supply fuel to the distributor will cause scor- 
ing of the disk and cover, since the distributor depends 
upon the fuel oil for lubrication. The engine will also 
cease operating because of insufficient fuel delivery 
(see pages 37-39). 

2. Repair. It is necessary to replace the disk and 
cover with a new or reground set when either shows 
scoring or wear. Disks and covers are supplied only in 
pairs, and must be replaced only as a unit. Due to the 
close tolerances existing, regrinding and lapping the 
disk and cover by operating personnel is not recom- 
mended. This operation must be performed at the 
factory where special equipment and trained personnel 
are available. When the disk and cover are being re- 
placed, they should be washed thoroughly with 
cleaning solvent, and all passages should be blown out 
with compressed air before installing. 

b. possible trouble: 
damaged metering pump plunger and barrel 

The usual trouble encountered with the common 
metering pump is a worn or scored plunger and barrel. 
A worn or scored plunger will result in a loss of pres- 
sure, causing inaccurate metering to the injectors. The 
power delivered by the engine will decrease. 

1. Causes and prevention. The causes for a damaged 
plunger are: 

(a) Dirt in the fuel. 

(b) Normal wear. 

(a) Dirt in the fuel. Dirty fuel will damage the 
metering plunger in the same manner that it damages 
the distributor disk and cover. The same precautions 
mentioned to protect the disk and cover from dirty 
fuel apply similarly to the metering pump plunger 
and barrel. The fuel system must be kept free of dirt 

(Jf) Normal wear. After many hours' use, the plunger 
will normally wear to the extent that the required 
pressure cannot be built up. If this is the case, the 
plunger and barrel must be replaced. To determine the 
extent of wear, the following simple test should be 
performed during disassembly of the unit. The pump 
barrel is closed off with a finger to test the suction. 
This will determine the fit and should be performed 
when the unit is dry. If the plunger is not held by 
suction for at least one minute, it is sufficiently worn 
to cause loss of fuel pressure and must be replaced. 

Digitized by GOUjllC 

2. Repair. Not much can be done to repair the plunger 
and barrel. A worn plunger and barrel must be 
replaced. However, a fine grade of crocus cloth may 
be used to polish and clean the surfaces, provided they 
are not excessively worn. 

When replacing a plunger and barrel, a new copper 
gasket should always be placed upon the end of the 
barrel . 

c. possible trouble: 


The priming valve is used in conjunction with the 
hand priming pump to prime the fuel system before 
starting. The valve is situated on the side of the dis- 
tributor housing. When opened, it allows fuel to 
bypass the metering pump and enter into the injectors. 
During operation, the valve must remain closed. If it is not 
kept closed, an unmetered quantity of fuel will be fed 
directly to the injector, causing excessive and uncon- 
trollable engine speeds. The importance of a perfect 
seal between the valve and the seat is therefore evi- 
dent. If the valve becomes damaged, there is danger 
that fuel leakage will occur, increasing the quantity of 
fuel to the injectors and causing the engine to run 
away. A fuel knock may be evident. 

The usual damage to the valve is a broken valve 
point or damaged valve seat. 

1. Causes and prevention. The above damage is gen- 
erally caused by overtightening the valve packing nut. 
If the nut is overtightened, the usual result is a broken 
valve point, which will allow fuel leakage to the 
injectors. Tighten the nut only to the extent that the 
priming valve can be turned with the fingers. The valve 
must be replaced if broken. 

If the seat has been damaged by overtightening, it 
must be repaired. 

2. Repair. If the priming valve seat is damaged, it 
must be refaccd with a J^-inch drill, ground to a 30- 
degree taper. See the Cummins fuel injector mainten- 
ance manual for the procedure in refacing the seat. 
Care must be taken not to remove too much of the 
stock. Only enough material to obtain a concentric 
seat for the valve should be removed. After refacing, 
all metal particles should be removed by blowing with 
compressed air. If the valve seat is damaged beyond 
repair, the distributor housing must be replaced. 

A broken valve must also be replaced. 

d. possible trouble: 
sticky injector plungers 

A sticky injector plunger may be characterized by 

Original from 


several conditions noticeable during engine operation, 
such as a missing or weak cylinder, smoky exhaust, 
and failure of the engine to develop full power. 

1. Causes and prevention. Following are the causes of 
a sticky injector plunger: 

(a) Improper fuel. 

(b) Uneven tension on injector hold-down nuts. 

(c) Interchanging plungers and bodies. 

(d) Improper service procedure. 

(a) Improper fuel. The fuel difficulties that must be 
guarded against to prevent sticky plungers are: dirty 
fuel, or fuel having improper specifications. 

A strainer screen is located in the fuel inlet connec- 
tion to each injector. The purpose of this screen is to 
remove any small dirt particles, etc., that may have 
escaped the fuel pump conical screen and the primary 
filters and strainers. This strainer screen must be 
cleaned occasionally to prevent the accumulation of 
dirt particles. 

Refer to a. Dirt in fuel oil, page 76, for care of the 
fuel pump conical screen. 

(b) Uneven tension on injector hold-down nuts. A sticky 
plunger may be caused by improper tightening of the 
injector hold-down nuts. They must be tightened to 
the same tension to prevent the injector body from 
becoming distorted. A distorted body will cause the 
plunger and its barrel to bind. The specified torque to 
be exerted on the hold-down nuts is from 10 to 15 
pound-feet. In attaining this desired torque, each nut 
should be tightened evenly in a step-by-step manner. 
Should a greater torque be applied to these nuts, there 
is danger that the valve seats may be distorted and the 
cylinder head cracked. 

(c) Interchanging plungers and bodies. The injector 
plunger must not be interchanged with another from a 
different injector body. Due to the close tolerances, 
the plunger and body must remain as a unit. The 
plunger must always be installed in its original injec- 
tor body to prevent binding and consequent damage 
to the unit. 

(d) Improper service procedure. Many injector troubles 
may be averted by careful service procedure. The 
injector must never be clamped in a vise, as a sticky 
plunger will usually result because of distortion of the 
injector body. A simple injector holding fixture can be 
designed, similar to that shown in the Bureau of Ships 
publication, the Cummins maintenance manual, in the 
section on the Cummins fuel system. This manual has 
been mentioned previously and should be used to ob- 
tain the proper service procedure required to prevent 
damage to the injector during overhaul and servicing. 

2. Repair. The injector plunger can be cleaned with 
a cleaning solvent to remove any carbon or varnish 
that might cause a sticky plunger. In this operation, 
clean cloths must always be used. 

If the cause for the sticky plunger is uneven tighten- 
ing of the hold-down nuts, the plunger will usually 
return to its normal position when the nuts are loos- 
ened and retightened properly. If the plunger does not 
return to its original position, the injector unit must 
be replaced. 

e. possible trouble: 
worn or scored injector plungers 

See Bosch Fuel System, a. Possible trouble: Damaged 
plunger and barrel assembly, pages 45~46. Omit 
cause c. Overtightening of delivery valve holder. 

f. possible trouble: 
clogged injector spray holes 

A clogged injector spray hole will prevent complete 
mixing of the fuel charge with the available air in the 
cylinder. Part of the air will be starved for fuel, that 
part being the amount usually supplied through the 
plugged hole. The other portion of the combustion 
chamber will contain too much fuel for the amount of 
air available in that area. These conditions will result 
in a drop in the power output of that cylinder, causing 
the other cylinders to attempt to carry the load. 
More fuel will then be delivered to the engine as a 
whole than can be burned efficiently, leading to sticky 
rings and crankcase dilution. Improper combustion 
will occur and smoky exhaust will result. The injec- 
tor spray holes must be inspected carefully when the 
injector is removed from the engine, to determine 
whether dirt or metal particles have clogged one of 
the holes. 

1 . Causes and prevention. See (c) Clogged nozzle orifices, 
pages 53-54. 

2. Repair. See the section on the Cummins diescl 
fuel injection system in the Cummins maintenance 

g. possible trouble: 
worn injector cup tip 

Wear of the injector cup tip, as shown in Figure 
4-38, can usually be detected by inspection of the cup 
under a magnifying glass. Figure 4-39 shows a new 
injector cup tip. 

1. Causes and prevention. The usual causes for a worn 
cup tip are: 

Digitized by tjOOQlC 

Origiral from 


sists af the accessary storage tanks, lines, filters, 
strainers, and transfer pumps (see the Atlas fuel system, 
Figure 4-41), 

ijajecnoa, the spray valve oiusr fee opened b:cr\ 

type (rsvo plungers), actuated by crosshciA* and con- 
— tmg nxk from a crank abaft bo! ted to ihr afrer end 

(b) Imprgpr service prwfdnri. Each engine is furnished •• /. 

with a cap cfe&mng fcic/ containing a brush, small :'" f& 

cleaning wires* a wire holder in the form of a pin vise, W 

andadrill^ , ^ ^ ^ 

high fuel prcssurc.creatcd rn the: cupdurijrg injection is 
exerted amuj^ the f&n&cA hole, and will wear £fae 

2, Repair. See the Cummin* Dmtl luti Injection 


4-40). This valve is of the bypass type, and utilizes a 
lapped needle valve and seat. A certain quantity of 
fuel is bypassed from the common rail at all times. If, 
for any reason, the fuel pressure within the fuel header 

drops, the spring pressure acting on the needle valve 
closes it slightly, causing less fuel to be bypassed and 
thereby maintaining a constant fuel pressure within 
the common rail. 

666202°— 46-7 

Digitized by 


Figure 4-42. Spray valve and actuating mechanism. 

Origiral frcrn 


The spray valve, Figure 4-42, a heavily spring 
loaded needle valve, meters the proper amount of fuel 
and delivers it to the combustion chamber at the 
proper instant in the cycle. 

The spray valves are actuated by adjustable cams, 
cam followers, push rods, and rocker arms. It can be 
seen from Figure 4-42 that the control of the time of 
spray valve opening and closing is obtained by the 
movable fuel wedge, which is actuated by the engine 
governor. To increase the engine speed, the governor 
moves the fuel wedge to decrease the gap between the 
cam followers and the push rods. This will cause the 
spray valves to open sooner, and close later, thus 
increasing the amount of fuel supplied to the cylinder. 
This increase in fuel will cause an increase in engine 
speed. The start of injection also occurs at an earlier 
time in the engine cycle, as is necessary with the in- 
crease in speed. To decrease the engine speed, the 
wedge is moved upward to increase the gap between 
the cam follower and the push rods. 

a. possible troubles: 


Improper timing is perhaps the most commonly 
experienced trouble with this fuel system and usually 
manifests itself in the form of improper engine per- 
formance, evidenced by black smoke, fuel knock, 
inability of the engine to carry the load, etc. 

1. Causes and prevention. This trouble can almost 
always be attributed to failure to follow timing instruc- 
tions. The engine instruction manual must be followed 
implicitly in order to time the engine satisfactorily. 

2. Repair. The proper method to be used in timing 
the spray valves to the engine is as follows: 

(a) The proper spray valve opening and closing posi- 
tions must be obtained from the engine name plate 
data. (In the following discussion, the usual values 
encountered will be used; that is, 8° before top dead 
center (BTDC) for opening and 18° after top dead 
center (ATDC) for closing.) 

(b) The cylinder isolation valves in the common 
rail must be closed to all cylinders except the one to 
be timed. 

(c) The buffer spring gage assembly in each fuel 
push rod must be unscrewed about two turns before 
any timing is performed. (This assembly, Figure 
4-42, assists the spray valve spring in returning the 
valve mechanism as the spray valve is closed, and it 
also serves to position the push rod in relation to the 
cam follower.) 

(d) The fuel wedges must be in the full load posi- 

Digitizes by G<X 'QIC 

tion. This position normally is attained when the 
engine is secured. 

(e) The engine should be barred over to a position 
halfway between 8° BTDC and 18° ATDC, which will 
be 5° ATDC. This position will be with the piston on 
the power stroke. The sliding fuel pump cam can be 
moved until the centerline of the cam toe is in align- 
ment with the axis of the cam followers. The cam 
must be clamped temporarily in this position. The 
cam is of the sliding type, keyed to the camshaft. The 
action of the spray valve is controlled by the steel cam 
toe, inserted in a steel disk, the disk serving as the 
base circle of the cam. 

(f) The crankshaft should be barred over in the cor- 
rect direction of rotation until the piston of the cyl- 
inder to be timed is 8° BTDC on the compression stroke. 

(g) Fuel pressure must be built up to 1500 psi by the 
hand priming pump. 

(h) The spray valve push rods are of the adjustable 
type; that is, they may be lengthened or shortened by 
loosening a lock nut and turning the push rod. The 
push rod must be lengthened until the fuel pressure 
drops, as indicated by the pressure gage. This will be 
an indication that the spray valve has opened, allow- 
ing the fuel charge to enter into the cylinder. 

(i) The closing point must now be obtained. It is 
well to bar the engine a few degrees past 18° ATDC for 
the cylinder in question before building the pressure 
up to 1500 psi in the common rail. The engine is then 
barred backward until the pressure again drops. This 
will indicate the closing of the valve. If the cylinder 
is in time, the flywheel indicator will be at 18° ATDC 
for the cylinder in question. If the reading is different, 
the length of the spray period will not be correct. If 
this is the case, it will be necessary to shift the slicing 
cam a slight amount, either to retard or advance the 
cam slightly, depending upon whether the spray 
period closing occurred before or after 18° ATDC. 
Then, steps (0 through (i) must be, repeated. 

(j) Each cylinder must be timed in a "Similar manner. 

(k) The buffer spring cage assemblies must be tight- 
ened and adjusted after the timing procedure. The 
buffer spring adjustments are listed in the engine 
instruction manual. % 

After the timing procedure, it is necessary to blow 
out the cylinder with compressed air, as a considerable 
amount of fuel will be in the cylinder due to the man- 
ner in which the engine is timed. 

After the above procedure is performed, the fuel 
system will be properly timed and balanced; that is, 
theoretically, an equal amount of fuel will be delivered 
to each cylinder at the correct instant. Actually, due 

Qrigiral from 


to mechanical difficulties, it is impossible for each 
spray valve to be in such perfect balance that each cyl- 
inder will carry an equal share of the load. This has 
led to frequent troubles brought about by attempts of 
operating personnel to balance each cylinder by ad- 
justing the push rod lengths, after the engine is in 
time. The engine manufacturer allows a slight adjust- 
ment of one-half turn of the push rod or less while the 
engine is in operation. If the rod is adjusted more than 
this amount, the start and stop of injection, that is, 
the timing, will be affected materially, leading to 
improper engine performance. The push rod length 
should never be adjusted more than one-half turn in attempting 
to balance the load of each cylinder while the engine is 

b. possible trouble: 
clogged spray orifices 

See Bosch Fuel System, (c) Clogged no^le orifices, 
pages 53-54. 

c. possible trouble: 


A leaky nozzle tip will cause unsatisfactory engine 
operation, as an excessive amount of fuel will be in- 
jected into the cylinder. This fuel will not be atomized 
sufficiently for efficient burning. Black smoke will be 
noted in the exhaust. A decided fuel knock may be- 
come evident. 

1. Causes and prevention. The usual causes for a 
leaky spray valve are: 

(a) Obstruction between valve and scat. 

(b) Damaged seat. 

(a) Obstruction between valve and seat. The seat for the 
needle valve is situated in the spray tip just above the 
entrances to the spray orifices. The valve body is 
counterbored to receive the spray tip, the tip being 
securely fastened to the valve body by a nut. 

Any piece of dirt between the seat and the valve will 
allow fuel to leak into the cylinder. This may be pre- 
vented by cleaning the tip and end of the valve stem. 

There are individual spray valve fuel filters to assist 
the fuel filter at the injection pump. These filters must 
be cleaned frequently by blowing with compressed air. 

(b) Damaged seat. If tip leakage still occurs after 
cleaning the seat and valve, the seat is damaged and 
must be either serviced or replaced. This damage may 
be due to the dirt or metal particles acting on the seat. 

2. Repair. Parts should always be handled with 
extreme care when cleaning the valve assembly. 
Should tip leakage still occur after cleaning, it will be 

necessary to reseat the needle valve by lapping the 
valve and its seat. This tip leakage can be detected by 
installing the spray valve on a fuel test stand and ob- 
serving the fuel spray. A fine grinding compound must 
be used for the lapping procedure. The ordinary case of 
leakage can usually be corrected by lapping the tip 
two or three times. 

If this does not stop the leakage, it will be necessary 
to install a new tip to replace the damaged seat. 

In installing the new tip, the joint between the 
valve body and the spray tip must be lapped in order 
to form a perfect seal. It will then be necessary to lap 
the new tip to the needle valve as mentioned above. 

d. possible trouble: 
worn spray valve packing 

This trouble becomes evident when fuel leakage 
occurs past the packing nut. This is an indication 
that leakage is occurring between the needle and 
its body. 

1. Causes and prevention. Worn spray valve packing 
is caused by : 

(a) Excessive wear. 

(b) Improper tightening procedure. 

(a) Excessive wear. Metallic packing wears after 
many hours of use and must be replaced when that 
wear becomes excessive. 

(b) Improper tightening procedure. The packing nut 
can be overtightened to such an extent that the needle 
may stick open. This is in addition to the damage that 
will be caused to the packing. The packing nut must 
not be overtightened. If leakage still occurs after the 
nut has been tightened, it will be necessary to replace 
the packing. 

2. Repair. Before replacing packing, the spray 
valve must be disassembled completely in order that 
all parts may be thoroughly cleaned. Graphite 
metallic packing of the metallic core type must be 
used, if available. If the metallic core is not available, 
plain graphite asbestos packing may be used. Only 
soft packing must be used. Stranded packing must not 
be used as the strands of metal in the packing will cut 
the needle. 

e. possible trouble: 
improper functioning of pressure 


If the pressure regulating valve is functioning im- 
properly, a constant fuel pressure reading cannot be 
maintained and the engine will drop off in power. A 
low or zero pressure reading will be obtained if there 

Digitize; by GOi Original from 



d«scripti.oft. Cooler 

:Se«cnicr cBV *• Ubncating oil di<»tf 15. Rea>l,*» sprmo , 

• <onnecfiqn Rwtcifor innw sleeve- ■ 

ot h«d m)CC- 5. Plunger 1?. Regulator »cck 

svsfciu, 'page 79. Ihc ioMowmg discussum is pcraucQC 11 0¥sdtb^» ii** connection S3. Dt^fiarge vow*- 
only r Q the contuu prfesut* svste*i».'**d on the 1* v«»*e ^ 


spring in the valve block. As the plunger is returned 
upward by the force of the plunger spring, a vacuum is 
created which exists within the barrel until the inlet 
ports are uncovered and the fuel oil forced in. The 
pressure of the discharged oil forces the regulator 
plunger, the push rod, and the rack upward against 
the pressure of the regulator spring. The position of 
the rack depends entirely upon the operating pressure. 

The amount of fuel oil that enters the barrel at each 
stroke is limited to the amount required to maintain 
the operating pressure. The exact amount of fuel is 
controlled by a pair of sleeves, one operating inside 
the other. The outer sleeve is attached to a linkage 
from the engine control shaft, and the inner sleeve is 
attached to a pinion gear that meshes with the regu- 
lator rack. In some models, the function of the inner 
and outer sleeves is interchanged. Ports in both 
sleeves permit the oil to flow. The inner sleeve is 
notched for measuring or metering small quantities of 
fuel oil. The amount of oil admitted at each stroke is 
dependent upon the existing fuel pressure in the ac- 
cumulator. The pressure acts on the regulator plunger 
to move the regulator rack, and hence the inner sleeve. 
When the pressure becomes too great, the rack will 
rotate the inner sleeve, causing the inner port and the 
outer port to coincide less and less. This restricts the 
flow of fuel to the pump plungers on their suction 
stroke, and therefore regulates the fuel oil pressure in 
the accumulator. 

a. possible trouble: 
pump fails to operate properly 

Failure of the pump to operate properly may be 
evidenced by loss of power, smoky exhaust, over- 
heating, and diesel fuel knock. These are only the 
first symptoms of improper pump operation. Con- 
tinued operation will result in excessive carbon de- 
posits, poor economy, and finally, in complete engine 

1. Causes and prevention. Improper pump operation 
can be due either to lack of maintenance, or to partial 
failure. The more common causes are: 

(a) Scored regulator sleeves. 

(b) Scored plungers and barrels. 

(c) Leaking discharge valve. 

(d) Leaking relief valve. 

(e) Regulator plunger sticking. 

(f) Improper regulation or assembly. 

(a) Scored regulator sleeves. The regulator sleeves 
arc required to shut off the flow of fuel to the pump 
plungers. The surfaces of the sleeves are accurately 

Digitized by GQoQIC 

finished, and fit closely with each other. The inner 
sleeve must be free to rotate within the outer sleeve. 
If it binds, it will prevent the proper regulation of 
the pressure, inasmuch as the regulator plunger will 
have difficulty moving it to open and close the control 
ports. Binding is due either to the formation of resin- 
ous deposits, or to foreign particles carried to the 
sleeve by the fuel oil or through carelessness when 
assembling. The particles tend to cause the inner 
sleeve to jam, and also to erode the ports, causing ex- 
cessive fuel to pass when it should be limited in 
flow. Water, if present in the fuel oil, will produce 
the same severe results. The fuel system is equipped 
with metal edge fuel strainers, and with fuel filters. 
The function of these is to trap and to hold all foreign 
particles of dirt, dust, metal, etc., that are in the fuel 
when it reaches the engine. The units will also re- 
move small amounts of water. Every precaution must 
be taken to eliminate these harmful elements from the 
fuel. All fuel strainers and filters must be inspected 
and cleaned as recommended in the instruction manual. 
All fuel having any water content must be centrifuged 
before being admitted to the day tank and to the fuel 
strainers and filters. 

(b) Scored plungers and barrels. The same factors 
that cause the control sleeves to become stuck and 
scored will also affect the plungers and barrels. The 
plungers and barrels are lapped together with only a 
minimum of clearance, and water, dirt, and other 
foreign matter have disastrous results on the lapped 
surfaces. Foreign particles may cause the plunger to 
jam, but usually will result only in excessive wear 
and leakage. 

(c) Leaking discharge valve. A leaking discharge 
valve will prevent the accumulator from holding the 
fuel delivered to it from the pump. If the valve leaks, 
it will allow the high-pressure fuel to flow backward 
when the pump plungers are on their suction stroke. 
This, depending on its severity, often totally prevents 
the pump from building up the required pressure in 
the accumulator bottle, which is usually about 5000 
psi. The discharge valve leakage may be caused by a 
scored or pitted valve and seat, broken spring, or a 
foreign particle lodged between the valve face and 

(d) Leaking relief valve. The system is equipped 
with a relief valve that is used only as a safety device 
to relieve the fuel pressure when it reaches a prede- 
termined value. Under normal operation, the relief 
valve remains closed. Should the valve become fouled 
with resinous deposits from the fuel oil, or should 
the valve and seat become scored, the high-pressure 

Origiral frcrn 




fuel will be bypassed, thus preventing the pressure The discbarge -valve and .scat are ma tched units, and 
from being budt up within the aariinularpc. are so marked. Like the plungers and barrels, the 

(c) ZwUtor plunder rt H the regulator plunger . *'-*»<^ -v^'^U^ 
or. the regulator rack, becomes ^rv»ck; proper pfe$$ure 
regu I a uor< of the high- pressure fosi within Uic'-acaim* 
uJatot Will fee prevented. Binding i 
resinous- stepe&jrrs on the arTceiei 
panicle that become wedged between moving parts. 

(7) tmfroptr rtgvlxthn or. assmbly, Whe^ regulating 

^ssembimg 5 fuei pump, the procedure outlined id 

X Repair When difficult.)- j* experienced with the 
hsgh-pressure fuel putnp, tt must be removed from the 
engine- and mmpkmly dissembled, Ail pam must 
be cleaned in dicsel fuel oil; it the parts -are discolored 
and appear tn hi* Acinous or carbon, deposits on 
ihar.i, they can best be cleaned in. carkiw wd lacquer 
reuioving compound (Fed. Std, Stoci Cat, No; 

!>6) ; After cleaning; the parts are inspected. 

small amount 

*f rouge should be placed on the 
plunger, and then > he plunger should t>e worked within 
the barrel (see Figure 4-44). All part* must be HM 
rhoroughly in dkscj fuel, to remove all traces of the 

rouge. Plungers and bMtth must am fee mrerchanged v 
as they are a selected" fit and ar#;*w fc . it> te^h^ngea We, 
The valves and valve se-jts i^t.'/'^eiaMry relief 
valves must be checked. The nuv be 

. '•.7.- . res Saw ~j 

• ,-\ ' 

.. 'J^jl ^^ ^S- ' - - • 

Fig»r* 4-46. Stjwor* loppAi* r»/f«f vo/r* j*or 4 

The regulating sleeves must b< checked see that 
they fit each other and die housing proper jy. They 

appreciable leakage If the skives are worn, it will be 
necessary to repine the h<mn\g and both sleeves. 

The remaining parr* muse checked for cracks, 
dirt Hid damaged threads. When reassembling, the 
instruction .manual must be followed carefully, 

4j9, the neevroufotef bottler. The function of the 
accumulator bottle is xa aid kt'majcvraimng.a omsUny 
fuel pressure by ofeing a brge volume of fuel at high 
pressure The pressure has a tendency to vary due to 
the inrcrnmterir tuel discharge and the p'u 

B. Control OmH coupling Fuel injecjor housing rA imoroDef 

Pw.*- ii7 ^ ^ improper 

nozzles is stopped immedmeh . The fuel iiuc pressure fcul to allow the waives- m sc4t when the cam kx&t 
is rheo reduced m eliminate a secondary in due ck&c- i$ on the base circle of the a*m. The usual cause 

....... \<- : : v.-; -:v."': ~: •:•<•: 


_..M - . , 

^'^ « T * w " tR • ••• •• % Vs 

... . , ■ | M 

1 .v- : s — 

- . M. mam* . 


, 1 




i pi 








•■ • ■ • . ' ^.^S / C 

stem cmnor be seen through the sight g to in rite sjdc All par ts should .be cleaned indtesci fuel, if gummy 
of the injector and dJscolorot. u uwv be necessary to ^carbon and 

W hen leakage isdueta Faulty ^aJsxs or vuive scats, lacque^^^ 

valve scats, lacquer d^ivi^ t^nvpourid (Fed, Std; Stock Car. No/ 

wirh /citeign fyrtides, the action of the, stem will be If roirtor parting has rake* place-* K can usuauy « rc- 

auggirfv, and in emein* ca$e$ will prevent, the valves moved Kv tapping on a f*pp>o£ plate with a fine lap- 

from closing This allows excess .fuel to be admitted pt rig compound The lower va) ve scat must be lapped 

to the 0 hmL-f . since the fuel cannot escape ' .'through with the valve stem in posrt ion (sec Figure 4-49). 
the hole w th? valve stem 


V «S <>> *> * 

arc: smoky .cxh-anst,; high or low c<jmbusiu.,n pressures" parts should be ringed thoroughly in fuel oil to remove 
or exhaust tempera turcs for one or mote of the cy\- M the rouge. The valve item is checked for excess 
indent; fuel knock ; or loss of power. wear by placing one fin— - ™, ,nd nf rW uWr 

inders; fuel knock; or loss of power. wear by placing one finger fiver one end of the lower 

2. Rtpjir. When engine operation becomes erratic, valve sear, another over the hole ip the valve stem, 

wear, arid to determine that the pu^h rod mov 
The miecror blocks rnust he disassembled as 


4K1, General dtocripffon. Pad lines used to bring 
the fuel from the rmks through the fad .manifold add 
to the fuel injecttod pumps axe a]]law-pre$$iire lines: 
Tfiese lines, must U nuvaamed in good condition if 
they are to give &*u*factoty &rvitt ^ ^ • 

submarines, be equipped with steel furf'IincsV SuV 
itiarines are permitted to use t 

to p*pc 

1, (W Mrf pmmm. (a) F*ft$w. Such break- 
ages-arc caused by the /inability of the nipples and 
V joints to withstand shock, vibration, and the 

stnaltef pipe* and the equipineiit to which they arc 


p.?] co the low rigidity of brass and coppery the ma ten At 

of replacement nippies should be stoel, njonei, or 
Cu-Ni T 4 " 't™ «-—*■ „«4 .-k* 

Br ' 


It is best to place fuel lines as far one of the way as 
possible. This docs not mean, however, that they 
should be placed in inaccessible pUces v as the : opposite 
is highly desirable. But they must not be placed where 
they will be walked upon, lacked, or struck frequently . 

Higii-ptessure Hoes are far more important: than 
they at tirst appear, for I iocs in improper coadmon are 

2. Repair. It is not enough just to replace the broken 
P*pc joint. It is also most important to take tt^.co. 
prevent rhc recurrence of the breakage. Wlwrre Irreak- 

The dfect of iiifTerenr lengths of tine is important. 
Varying the length of the Hoes makes i? possible to 
change the injection characteristics. An taction 
pump and nozzle will have a different injection delay 

; Gencr41y,^t 0 otalwa^aninci^ialiiicl«gA 

. , rt . will mcrcajc the injection delay. Sometimes it is found 

shoulo be adopted. ^ jf>acasiog thc Hnc Icngth dccreases ^ J^on 

delay. The magnitude of injection delay is highly 




"Mscrawww distance between a given pump and its nozzle is shorter 

than the greatest distance between other pomps and 
their cor 


ftSm back. When tinea are so doubled 

port must be provided ro prevent them from 

. • 1 - ■ : ■ ■ - .■ ' , 

<SCA! >NC . SFAV.INft ~ 




Satisfactory repair, in cases of emergency, can usu- 
ally be made by soldering a new fitting to the line. 
Silver solder must be used, and great care must be 
taken to insure that the center of the fitting and the 
center of the line are properly located. Extreme care 
must also be taken to prevent the solder from clogging 
the line, as capillary action, tending to draw in the 
solder, is likely to produce such clogging. After repair, 
the line should be tested for lealcs and to make sure 
that the line is open. The silver soldering of new fittings 
on the line is to be done only in cases of extreme emergency. 

Section 4. Filters and Strainers 

4M1 . General description. Fuel filters, in the 
Navy, arc replaceable absorbent cartridge devices em- 
ployed to remove harmful particles from the fuel. 
Cartridges are constructed either of cotton yarn, cot- 
ton waste, paper disks, wood pulp, or some combina- 
tion of those materials. Fuel filters are extremely im- 
portant in preventing destruction of critical and ex- 
pensive injection equipment caused by abrasive par- 
ticles in fuel. 

Filters and strainers built into injection pump or 
nozzle housings are discussed under the pump or 
nozzle concerned. 

a. possible trouble: 
filter clogged before 500 hours* operation 

In certaininstances, filters will become clogged prior 
to 500 hours of operation. 

This condition docs not indicate malfunction of the 
filter. On the contrary, a filter that is clogged is one 
that has performed its function well. This condition 
may be evidenced by stoppage of fuel flow, increase in 
pressure drop across the filter, increase in pressure up- 
stream of the filter, or by excessive collection of dirt on 
the element, observed when the filter is dismantled for 

Definite rules for changing filter elements cannot be 
established for all engines. The 500-hour rule is only 
for average conditions, and will not apply when 
unusually dirty fuel with solid content above .005 
percent is extensively used. 

It must be remembered that the symptoms of clogged 
filters will vary in different installations. Each instal- 
lation should be studied, and the probable external 
symptoms anticipated. Among these symptoms will 
be instrument indications, engine operation, etc. If it 
appears that no external indication will be apparent, 
then the elements must be inspected visually whenever 

Digitized by GOuQIC 

there is any reason to suspect that dirty fuel has been 
taken aboard. 

1. Causes and prevention. Filters may become clogged 
before they have been in operation for 500 hours 
because of: 

(a) Use of unusually dirty fuel. 

(b) Filter capacity too small. 

(c) Failure to drain filter sump. 

(d) Failure to use primary strainer. 

(a) Use of unusually dirty fuel. If dirty fuel is taken 
aboard it will clog the filters in a short time. Care is 
necessary to insure that hoses, fittings, and other gear 
employed during fueling are absolutely clean. Many 
fuel supply ships and depots are equipped to filter fuel 
as it is being delivered. This will eliminate consider- 
able dirt, and this procedure should be used in fueling 
whenever possible. Tanks should be inspected for ac- 
cumulations of sludge and water before refueling, and 
cleaned as prescribed on page 97, if necessary. Fuel 
should be centrifuged before use if facilities are avail- 
able. If facilities are not available for centrifuging the 
fuel, settling tanks should be used and water bottoms 
drained regularly. 

(b) Filter capacity too small. A small filter will clog up 
more rapidly than a large one because it does not have 
so much space available for accumulation of dirt. 

The Bureau of Ships has now standardized on two 
fuel filter element sizes, for use on all engines con- 
structed in the future. The large size, designated as 
Navy Standard, is about 3 inches in diameter by 
8 inches in length. The small size, designated Navy 
Standard {smalt), is also 3 inches in diameter, but the 
length is 4 inches. Construction is such that two 
Small elements can be stacked for use as one Standard 
element. One Small element has a capacity of 25 gal- 
lons per hour; the Standard, a capacity of 50 gallons 
per hour. 

Filter capacity should at least equal fuel supply 
pump capacity. 

(c) Failure to drain filter sump. Most Navy filter cases 
are equipped with drain cocks at the bottom of the 
case, for the purpose of removing accumulations of 
sludge and water from the sump. If water is allowed 
to accumulate, it may carry over with fuel and cause 
damage to injection equipment. Removal of dirt 
through the drain cock will make room for more dirt 
in the filter. 

When the filter is on the discharge side of the fuel 
supply pump, as is the usual case, the sump should be 
drained, while the engine is operating, by quickly 
opening the drain cock wide until all sludge and water 

Qrigiral from 

tjons rnnsr he equipped wjch rwc s stamen of filtration,'' H 
and should be -..equipped mxh, sriditiDnal stage* if 

The priffla/y: stage ge$ef>iU# consist* of jticral edge 

2 fcjM*?. a.filter is dogged, .it is ncces&arv to 


j j^..^ the iiijccsioft cquifMncat when the tngnic h started. 

$ immersed in cte>u? tipna>crpsive 
n.tph th a d ieseJ fuel kerosene, etc) 
? wiis are scrubbed from .'the <M$tsideof the 
element. It CArioot he- expect.e* 
If the duplex system « used, a dirty titer dement -will remove deposits horn |$5 
~ '' * 1 ■ ■ 1 : deaning 

c removed, aJJ rraces of cleaning 
:->;j from the element wi'eh clean 

are turned to pcsiuon No, JL Normally, hirers No. J diesel 
and No. 2 arc not used at the same tirne. One acts as a meat 



This procedure is not to be used except fa fctscs of pressure to flow through even a pin hole m the piping 



. : 

in list never be possible for UVc UM to (low from the 

Am in totes 

gaskets should be checked. If copper tu hi ng is used, it 
should be- checked carefully for cracks which may 
have hecrt. caused by coiisunt vjbratioa. filter* located 
in tfiewvcxw i inc. must be uupe^ccd carefully for leak * 
ogc. The sua mo (me m kept in good .condufptf 
to ^Vi>iJ tfouWc of tht^Tcnd 

(>) Eji&tit rphs out nj fi*H When the engine is al- 
lowed rqj run our of fuel, the level in the day lank ftlis' 
below the end ot the suuian piping This allows air 
instead of fuel to be dtuwa into the suction line This 
be pumped into the filters, and thetfee to 
ressuie fuel pumps. At this point the?. -engine 
to stall. 

When ir is desired to resume operation after tilling 

fuel . pomps and hoes. Expansion and compression of ( c ; } i, ak m trailer Pump. A leak in rhe pump shaft 
this air may occur widrout the opening of rhe nneo "packing, Or 

wob valve m maw snm When ih is condition. i>e- 

c.vut, the pun T >..umy ^ -us* ,^..«f#*f> K.ecMtrencc n tms crouDie rr 

The presence of air in the iiher may ht verified bv niaimainnjg die. pump in good 
• bleeding a small amount of fuel from the mp of the 37 42V 

£0 ht aJt' ^unJ^ 

past faulty pump gaskets, may allow air 
to be drawn directly into the fuel transfer pump. 
Recntrence of this trouble may be prevented by 

condition ("see pages 

bnbbics of iii cnrrarM in rhHue. and che ™ steps take, | H| air 

I. Cms* and prtvmtmi. Air may enter the (liter by from entering the system again, 
a. number of means ft should be remembered chat in Several methods of priming the fad syst^ife* Or 
order for air from the atmosphere to enter a fuel line, purging it 0/ all , may bt used, if the filter is prac- 
tise pressure wit hin that fuel UflS must be below at- deafly filled with air., it wii) usually be advisable, -4% a 
mqspheDcr, pressuxe. Consequently, the most logical time sa-vet, to remove the filling plugs from the top of 
•pUce to anticipate carry of air into the fuel system is 
on rhe suction side of the fuel transfer pump .Its mc 
■insuliauoa*;. the pressure wif bin thr sucuon line 
below armosphetic pressure. priming pump. 

The most usual causes of entry of air 'wo the fuel When only a small amount of air i$ trapped in the 

hirer are; fuel system u may be possible to remove it by one of 

• t» Xc*k Jn tooufcr pump suction piping. the following mecbods; 

(e) Leak in 
(a) il«v»4 /rfeajj 
pressure v.-iihin the 
pheric pressure, airjo 

.:< w >: . 

(fc) Most installations have a hand operated transfer 
pump to facilitate priming; The txacc proce 1 
priming a system by use of this pump varies 
deciding on the construction of the system. Gener- 




illy, however, the procedure is to remove the ait p*o- c * ntou&Lfc; 

grcssivdv ftwn sil pares <»f the $\>$tem> suning wv:h . lea ky tilt^r. -gASS- 

chc s^o, U*e ,rf-thc .r.ns/er pump, .nd p t ^n g Th , s trouWe isqu ~ 

tottK tD^ w.H • ^ pirn, or flowing of fud from che fud ftlrcr case, LT n k$s. 

Take . : th* - ^yum. ulustmsd to Bgyrt 4-55 an * t . 3 ., . . 

, • v the leak is severe, engine opemuott n not melted 

example; ( , , t , . r . . * 

~. . * * j » i however r s^xj leakage must be eiujomat cd 

closed ar point 1 

cloudy, fuei is issuing from the line. The line is then 1, frtwntton. In .ntost Ca$e^ k is difficult 

to determine the cause of leakage-, However, some 

h then opened at. point 3 and the pump; 
operated until aiWrec fuel issues from the line If.thfc' 

(c) Overs tressmg of 

(d) Overtightening of the screw fastenings, 
'ft I iter ot.sWin^f' i$ almost compiexety tilled with air, it (a) -Poor "condition of thi ^tska Practically a H fuel 
will usually .sav*... rime and labor to fiil the Ivltcr or. til ters havt gaskets; usual \y cork, between at) joints in 
strainer by pouring fuel in through ihe rilling plugs in thz case.. When the filter is dismantled for renewal of 

" the dement; . these gasket s must he ins peered carefully 

th$ top, The tine is then dosed at point } 

transfer pump; hack to the (ml supply tank, and to aid assembling the fi\ ia r can: mast be taken to insure that 

in the constant removal of small amounts of air in the the gasket b properly positioned, 

fuel. The hand pump is operated until the pump hous- '(b) Com s ion of the cm* Corrosion may be the result 

i«5 is cleared of. air In sma!) high-speed engines, this of . failure, to drain the him sump- Accumulation of 

may be ilj the priming necessary^ Since rhc priming fit, water ar that point facilitates corrosion, When corro- 



^ : 


^ • • '.'y,r \A .' » 


Tim croubleisciujiJv rccogmzcd us the sh.i/r, blades, 
or the handle employed to aw n the scrapmg mechan- 
ism is broken. , and k )_$ impossible to rotate the scraper 
element When this occurs, »c is intpossihle to clean the 


C 5 V:t:.. 

• filter readies jrs capacity, it allows , the warn- to pass 
through with the fuel oil 

5, evidenced bv coasukrAble d'ith- 


waste fuel which is an important item and must be 

1. Causes and prevention. There are two principal 
causes of tank leakage: 

(a) Improper weld. 

(b) Fatigue. 

(a) Improper weld. Quite often, the underlying cause 
of a fuel tank leak will be a substandard weld at one of 
the joints. Proper welding technique must be em- 
ployed to prepare standard welds. 

(b) Fatigue. Improper support will cause excessive 
stresses in the tank, resulting in cracks. All tanks must 
be supported properly. 

2. Repair. Although leaks are hard to foresee, it is 
important that a leaking tank be repaired at the ear- 
liest opportunity, to prevent the crack from spreading. 
Tanks are repaired by welding and preparation for 
welding is important. Before any welding can be 
undertaken, the following precautionary measures, 
from the Bureau of Ships Manual, must be observed. 
These precautions arc for the protection of the repair- 
man and the crew, and must be complied with. 

Chapter 55, paragraph 31 (k), of the manual follows : 

(k) Whenever a fuel-oil tank is to be entered, or whenever any 
work is to be done in it requiring heated rivets, hammering, etc., or 
any lights other than portable electric (electric lights shall be fitted 
with gas-tight globes and heavy wire guards and shall be tested for 
complete insulation before use), or whenever such work is done in 
the vicinity of open tanks, or pipes, all such tanks and all pipes lead- 
ing to or from such tanks shall be cleared of vapor, after the fuel oil 
has been removed, by flooding with water, followed by blowing 
through with air for at least 12 hours by means of a portable blower, 
or by blowing through with live steam. In using live steam, due 
regard must be given to the liability of overheating adjacent com- 
partments, such as magazines, storerooms, etc. After blowing 
through with live steam, all manhole plates of the tanks shall be 
removed, and the tanks ventilated by means of a portable blower for 
at least two hours. No person or persons shall enter a fuel-oil tank 
for any purpose without obtaining permission, each time, from the 
commanding officer, who shall assure himself that the tanks are safe 
to enter, and then anyone so entering such tank shall have a life line 
around his body, properly tended, in order that he may be hauled out 
if overcome by gas. Fuel-oil tanks shall be continuously ventilated 
by means of a portable blower during the time that work is being 
done in them. 

B. POSSIBLE trouble: 

When fuel tanks are not filled with sea water for 
ballast, the rate of corrosion should be slow and offer 
no particular difficulty, as the fuel oil itself tends to seal 

the surface, thus preventing oxidation and corrosion. 

When fuel tanks are also used for sea-water ballast 
space, the rate of corrosion will increase and the ex- 
pected life of the tank will be considerably less. This 
type of tank must always be kept filled. By keeping 
the tank full, the free surface is eliminated, adding 
greatly to the stability of the ship, and eliminating the 
air which supports rusting. 

1. Causes and prevention. 

(a) Presence of oxygen. Causes of rust are obvious 
when the dicsel fuel tanks are used for sea-water bal- 
last tanks, and the relatively small amount of rust in 
the other type is not objectionable. 

Prevention of rust, however, is a difficult problem. 
No type of paint yet developed is serviceable as a pro- 
tective coating. The diesel fuel will attack any known 
material which can be applied. A diesel fuel tank must 
never be galvanized despite the fact that the zinc coat- 
ing will reduce the rust in the tank itself. 

2. Repair. When tanks have corroded to the extent 
that they leak, it is highly improbable that satisfac- 
tory repair can be made by welding or patching. When 
corrosion has developed to such an extent in one spot, 
there are generally many other spots in the tank on the 
verge of rusting through. The only sure method of 
repair is to replace the tank. 

c. possible trouble: 


Some trouble has been experienced with rusting 
through of suction and vent lines. 

The suction line failure will prevent oil from being 
drawn from the tank, and allow air to be admitted to 
the system. 

1. Causes and prevention. 

(a) Presence of moisture. The rusting is caused by 
moisture present in the upper spaces of the tank. When 
replacing the suction and vent lines it is important to 
make certain that they are not replaced with galvanized 

2. Repair. Repair should be made by replacing all 
the suction or vent lines with steel piping. 

Digitized by GOoSl^ 





5 A1 . Introduction. The speed control system con- 
sists of those engine parts designed to maintain the 
engine speed at some exact value or between desired 
limits, regardless of changes in the load on the engine. 
Diesel engines perform most efficiently when speed 
variations in service are small. Constant variation of 
engine speed tends to accelerate engine wear and results 
in reduced efficiency. 

Propulsion engines ordinarily do not experience 
much change in loads when the throttle setting is un- 
changed. Governors are provided, however, to control 
the speed of the engine before it is coupled to the pro- 
peller, and to prevent overspeeding in rough seas when 

the load might be suddenly reduced by the screw leav- 
ing the water. 

In electrical applications it is frequently necessary 
to control engine speed with great accuracy in order to 
maintain constant frequency, or to distribute the load 
between two engines in parallel. Hydraulic governors 
arc generally employed when such accuracy is required. 

Governors maintain idling speeds sufficiently high 
to prevent stalling and the consequent hazard of a 
dead engine in an emergency. 

Most governors and all overspeed trips arc designed 
to prevent engine speeds from increasing to such a 
point that inertia forces pull the engine apart. 

5A2. General description. Mechanical governors 
in use in the Navy are generally the spring loaded fly- 
ball type. The centrifugal force produced by rotation 
of the flyballs is transmitted by suitable linkage to the 

governor mtchanisms. 

Origiral frcrn 



fuel pumps, wing in * direction ta r*Wc fuel input imiunitf- 1 
co the engine. Sj 
and 'sets- m * * 

Ail mechanical governs uzve spied Jtify This mechanical govcriiui $ One-, known a& the 
nieam that as the loud is increased , at cp'nsiam th rattle . gpvrrMr* vised an generator ' sens, is designed 


chronaus. Coosc^ucrntly, mcch^jed pernors .ire manual adjustment. The following < 
never ased wh^ astutely cons^o^pced regulation . be found applicable, ir *" 

is necessary . 


governors ft w.Jl be noted, however, chat there is no 
. The buffer spring adjustmenton theconit.HH speed governor 

•Ipusc be' toil owed in a^se^ifW-trigxhe. governor 
; C2) Reauemhlm^ Uusrn^ to m^nt -wtt*> parts in dm? 
| cmdiuon. Dirt mods to c.<use diu* and binding: This 

: . . •-.vr' s;: '.^. ■..>-••<: ^ 

HIGH *P££Q F^PP*' > Lw |f^-tp. farf OiK kerosene e,. j and \Mshcd ihuraugto/ again 

FLYWEIGHT^ I FyWEIGHiS, before r^ssanhlv ^ Decc$sarv U is -advisable iocoai 

Haute 5^2. G .M. fliftirAtfiMW- ««v^dr. the spl ities. with grease before enea eio je them in the 


hollow blower shaft. This will tend to cushion shock 
loads to which the splines are subjected. 

(3) Placing operating yoke (forked lever) between 
thrust washer and balls of thrust bearing. This will 
quickly ruin the thrust bearing, and may cause the 
shaft to bind and place undue stress on splines. This 
precaution is emphasized in the instruction manual. 
The reassembly instruction in the manual must be 

(b) Poor condition of the shaft bearing. Freezing of the 
shaft bearing imposes high loads on the splines and 
may cause them to fracture. Any poor condition of the 
bearing that increases the friction also increases the 
load on the splines. Trouble can be prevented by 
careful inspection of the shaft bearing prior to assem- 
bly. It must be made certain that the bearing is per- 
fectly clean before assembly. Refer to Chapter 16 for 
hints on ball bearing inspection. 

2. Repair. The governor drive shaft should be re- 
newed, and all other governor parts inspected for 
burring, scoring, bending, or breakage. It may also be 
necessary to renew the hollow blower shaft if the 
internal splines are damaged. In renewing shafts, 
effort should be made to select two that fit well. The 
condition of the spline should be inspected with great 
care; shafts with dented, worn, or otherwise distorted 
splines should be replaced to prevent failure in service. 

b. possible trouble: 
broken high- or low-speed springs 

This trouble is recognized by a sudden drop in en- 
gine speed, usually resulting in stoppage of the engine. 
Since the spring force acts to increase the fuel input, it 
is easy to understand why the engine speed drops when 
the speeder spring breaks. 

1. Causes and prevention. Spring breakage is due to: 

(a) Failure to inspect the springs carefully. 

(b) Nicking or scratching springs. 

(a) Failure to inspect the springs carefully. Whenever 
the opportunity presents itself, springs must be care- 
fully inspected for nicks, checks, scratches, cracks, or 
distortion. Any spring showing such imperfections 
must be replaced with a new one. Even the most insig- 
nificant nick can cause failure. 

(b) Nicking or scratching springs. Springs should be 
handled with reasonable care to avoid nicking or 
scratching when the governor is disassembled. Careful 
inspection will prevent installation of defective 
springs when the governor is reassembled. 

2. Repair. The defective spring should be replaced, 

and adjustment made of the idling speed, maximum 
speed, and gap clearance. 

c. possible trouble: 


This trouble may be indicated by faulty speed con- 
trol. Hunting is frequently caused by looseness of the 
internal or external governor linkage. It should be 
remembered that the theory of governing is based on 
the premise that every change in position of the fly- 
balls will cause a corresponding change in the fuel 
quantity control mechanism. If linkages are loose, it 
may be possible for the flyballs to change their posi- 
tion without effecting a change in the fuel quantity. 

1. Causes and prevention. The most frequent causes of 
excessive wear of these parts arc : 

(a) Failure to keep the parts clean. 

(b) Failure to insure lubrication of the parts. 

(a) Failure to keep the parts clean. Accumulations of 
dirt between, or in the vicinity of, contacting surfaces 
of the governor internal or external linkage will cause 
a lapping action and will result in greatly accelerated 
wear. To prevent this action, all parts must be cleaned 
thoroughly at periodic intervals. This applies particu- 
larly to control shaft bearings. 

(b) Failure to insure lubrication of the parts. The lower 
portion of the governor is lubricated by splash from a 
slinger on the lower rotor shaft. The oil level at this 
end of the blower must be sufficient to allow oil to be 
splashed onto the governor parts. Make certain that 
the two holes, at each end of the blower housing, which 
allow oil to come from the camshaft pockets in the 
engine head to the blower, are clean and clear. The oil 
slinger should also be checked for its condition. 

The upper portion of the governor is lubricated 
partly by oil from the lower portion, and partly by oil 
from the cylinder head control link passage. 

The external linkage is lubricated by oil within the 
cylinder head cover. It is advisable to pour some oil 
over the bearings at the ends of the control tube when- 
ever the cylinder head cover is removed from the 

2. Repair. All worn parts must be replaced if the 
governor is to function properly. Great care should be 
taken to insure cleanliness when replacing parts. 

d. possible trouble: 
binding in governor or linkage 

This trouble is recognized by hunting of the engine, 
or may be revealed in inspection prior to starting the 

Digitized by GOOQle 0Mginal fr ° m 






good cylinders, but rather to place the faulty cylinders 
back in operation. 

f. possible trouble: 

high-speed spring tension adjustment improper 

This trouble is reflected by engine speeds lower or 
higher than rated speed at full throttle. However, 
inability to reach rated speed, sometimes referred to as 
loss of power, is quite frequently caused by malfunction 
of engine parts other than the governor. 

1 . Cause and prevention. Improper high-speed spring 
adjustment is generally due to ignorance of adjust- 
ment procedure. It is extremely important for the 
operator not to increase high-speed spring tension 
immediately by adding shims when it appears that the 
engine will not reach rated speed at full throttle. If 
this is done, it is quite possible that the trouble caus- 
ing the loss in speed, which might be faulty engine 
parts, may be remedied at some time after the governor 
adjustment is made. As the maximum speed has been 
raised by adding shims, the engine may then reach 
dangerously high speeds. A check should always be 
made for trouble from other sources before adding 
shims behind the high-speed spring. In rare cases, it 
will be necessary to alter the spring tension adjust- 
ment when the engine will not reach rated speed. 
When the engine speed is too high at full throttle, and 
there is no sign of breakage in the governor, it is likely 
that there is too much tension on the high-speed spring. 

2. Repair. The high-speed spring tension must be 
adjusted as directed in the instruction manual. If 
engine speed is too high, shims should be removed 
from behind the high-speed spring. If it has been 
ascertained that insufficient engine speed is caused by 
improper governor high-speed adjustment, it will be 
necessary to add shims behind the high-speed spring. 
In performing the latter operation, too many shims 
must not be placed behind the spring. 

g. possible trouble: 
improper gap clearance 

This trouble is recognized by so-called flat spots in 
the curve that may be plotted of governed speed versus 
governor lever travel. This means simply that at a certain 
speed, as indicated on the tachometer, a change in the 
position of the throttle will not result in a noticeable 
change in engine speed. The speed at which the flat 
spot occurs may indicate whether the gap clearance is 
too great, or insufficient. 

1. Cause and prevention. Improper adjustment of gap 

Digitized by GQoQIC 

clearance is due to ignorance of adjustment procedure. 
Gap clearance should not require frequent adjustment 
unless the governor is disassembled frequently. Unless 
the procedure set forth in the instruction manual is 
followed exactly, it will be difficult to make proper 

2. Repair. The gap clearance adjustment is made as 
specified in the manual. Care must be taken not to 
overspeed the engine if the adjustment is made while 
the engine is running. If a flat spot occurs. at about 
1200 rpm, it is likely that the gap clearance is too 
wide. If a flat spot occurs at about 800 rpm, it is likely 
that the gap clearance is too narrow. 

h. possible trouble: 
buffer screw adjustment improper 

This trouble is reflected by a rolling variation in en- 
gine speed when idling. The buffer spring has the 
function of dampening oscillations of the differential 
lever. It is necessary that the buffer spring screw be 
screwed in sufficiently to dampen the roll without 
adversely affecting the governor operation. 

1. Cause and prevention. Improper adjustment of 
buffer screw is due to ignorance of adjustment proce- 
dure. The procedure for buffer spring adjustment is 
covered fully in the instruction manual. Whenever 
idling speed is adjusted, it will be necessary to readjust 
the buffer screw. 

2. Repair. In performing the adjustment it must be 
remembered that the buffer screw is to be screwed in 
only far enough to prevent rolling. If the buffer screw 
is screwed in too far, it may be impossible to shut 
down the engine. 

5A4. Pierce mechanical governor. This governor 
is of the spring loaded centrifugal type. The centri- 
fugal force produced by rotation of the flyweights acts 
in such a direction as to reduce the amount of fuel sup- 
plied to the engine. This force is opposed by the 
speeder spring, generally located outside the flyweight 
housing. The force exerted by the speeder spring acts 
in a direction to increase the amount of fuel going to 
the engine. 

Like all mechanical governors, this governor has speed 
droop. However, unlike many mechanical governors, 
the amount of speed droop of this governor may be 
adjusted. This feature allows the governor to be used 
for parallel generator operation. The construction of 
this governor is simple, and adjustments are readily 


Origiral frcrn 

ANN • 



Oi mm l . i 

f J 

? I t 





k. po&uyuz trousle: ~ broken 'txr loose fly weights is failure XQ inspect the 




only. If new flyballs arc installed, the proper size 
must be used. Generally, aboard ship it will be found 
most expedient to replace the entire governor when- 
ever such extensive repairs are necessary. The dam- 
aged governor should be taken to a repair ship or base 
for reconditioning. 

b. possible trouble: 
worn shaft bearings 

This trouble is recognized by inspection of the bear- 
ings upon disassembly of the governor, by excessive 
friction when the governor shaft is rotated by hand, or 
by erratic speed of the engine at constant throttle 
setting. Continued operation of the governor with 
scored or otherwise worn ball bearings may lead to 
stripped drive gears, scored shaft, or scored thrust 
sleeve. Wear of the upper bearing may also lead to 
excessive wear in the weight pins connecting the fly- 
weights to the spider. 

1. Causes and prevention. Wear of shaft bearings is 
due to : 

(a) Failure to clean the governor frequently. 

(b) Insufficient lubrication. 

(a) Failure to clean the governor frequently. Dirt is the 
prime enemy of governors. Proper performance of the 
governor is impossible if dirt is present. Whenever 
possible, the governor should be cleaned thoroughly 
in carbon tetrachloride or other clean noncorrosive 
solvents. A governor should never be assembled unless 
it is certain that all parts, particularly the bearings, 
are absolutely clean. Bearings should be inspected 
carefully during each disassembly for wear. This is 
done most readily by comparing the bearing with a 
new one. The balls and races should be inspected for 
signs of pitting or scoring, and replacement made im- 
mediately of any bearing exhibiting such signs, in 
order to avoid more serious consequences. 

(b) Insufficient lubrication. Most Pierce governors in 
use by the Navy today have lubricating oil lines or 
passages to conduct oil to parts requiring lubrication. 
It is important that these lines and passages be main- 
tained in a clean and clear condition. A check for 
clogging or restriction should be made whenever the 
governor is disassembled. The use of clean lubricating 
oil at all times will reduce the tendency of passages 
to clog. 

2. Repair. Worn bearings may be replaced if facilities 
arc available for doing so. If not, it will be most 
expedient to install a replacement governor and have 
the damaged governor reconditioned by a base or ship 
having the proper facilities for such work. 

c. possible trouble: 


After prolonged usage of the governor, wear may be 
evident on that face of the thrust sleeve in contact 
with the flyweight tips. Sluggishness or rough opera- 
tion of the governor may indicate scoring of the thrust 
sleeve face. 

1. Cause and prevention. Scoring of thrust sleeve 
face may be due to the poor condition of the upper 
shaft bearing. This condition results in a tendency of 
the thrust sleeve to fail to rotate with the spider. This 
will cause relative motion between the flyweight tips 
and the thrust sleeve face, with consequent wear of 
the face and additional stress in the spider. The bear- 
ings must be kept in proper condition by frequent 
cleaning and inspection. 

2. Repair. As the thrust sleeve may be replaced 
without special tools, it may be possible to make this 
replacement aboard ship. When making this replace- 
ment, it is necessary to make an inspection of the fly- 
weight tips or noses that bear on the thrust sleeve face. 
These noses should be smooth with a ground radius. 
If undue wear has occurred on the noses, it will be 
necessary to replace the flyweights with another pair 
of the same weight and dimensions. 

d. possible trouble: 
improper adjustment of pump control 


This trouble may be recognized by checking the 
governor and fuel pump immediately after placing the 
governor in position on the engine. If it is found that 
when the governor lever G is moved through its arc 
and allowed to come to rest, the fuel pump control rod 
is not so positioned that the pump will discharge the 
maximum amount of fuel, it will be necessary to ad- 
just screw D. 

1. Cause and prevention. Improper adjustment is 
usually the result of ignorance of adjustment proce- 
dure. Adjustment of screw D may be necessary when- 
ever the governor is removed from the engine, or when 
new parts or assemblies are installed in the governor 
or fuel pump. The adjustment should be made in ac- 
cordance with the repair procedure outlined below. 

2. Repair. Adjustment of the positioning screw D is 
the first adjustment that is made on this governor. It is 
made as follows: 

(a) The governor is installed and the oil line, if any, 
is connected. The governor spring is hooked to the 
throttle control, and the governor lever G is connected 

Digitized by GOOQle 105 



to the pump control rod. With some tension on the 
governor spring, and screw D adjusted so that lever 
G is in the middle of the fork (engine not running), the 
pump control rod is adjusted so that it is in the wide 
open position. 

(b) The governor spring is released and the gover- 
nor lever G is worked throughout its stroke. The con- 
trol rod should always return to the wide open posi- 
tion when lever G is moved toward the governor. If 
some slight change of setting is required to accomplish 
this, screw E is released, screw D is adjusted again, 
and screw E is again secured. 

(c) A careful check is made to see that the lever G is 
still near the middle of the fork. Screwing too far in 
on screw D may cause breakage of lever G when the 
load on the engine is suddenly reduced. 

e. possible trouble: 
improper adjustment of speeder spring tension 

This trouble is recognized by an engine speed at full 
load that is either too high or too low. As always, 
before making adjustment on the governor, it should 
be ascertained whether the improper speed is due to 
other engine factors such as missing cylinders, etc. 
Speeder spring tension must be correct if the governed 
engine speed is to be at the proper level. 

1. Cause and prevention. Improper adjustment may 
be due to ignorance of adjustment procedure. It is 
necessary to follow adjustment instructions exactly if 
successful performance is to be attained. The instruc- 
tion manual must always be used to aid in the solution 
of engine problems that arise. 

2. Repair. If the engine speed under full load condi- 
tion and at full throttle setting is too low, and the 
engine is in good condition, it indicates that the 
speeder spring tension is too low. To increase speeder 
spring tension, the knurled nut, A in Figure 5~4, is 
turned down, or clockwise, after first loosening lock- 
nut F on the spring tension adjusting eyebolt. The 
locknut is then run up tight against the eye of the 
adjusting screw B. This adjustment is repeated until 
the desired speed at full load is attained. It should 
be remembered that changes in settings of other ad- 
justing screws on this governor will affect full load 
governed speed of the engine. For example, a change 
in the speed droop adjustment will change the maxi- 
mum speed of the engine. Consequently, both must 
be adjusted in small increments, returning to full load 
and speed after each small adjustment to recheck 
maximum speed; then the load is removed from the 
engine and the speed droop is determined. For infor- 

Digitized by GOOQle 

mation on adjustment of speed droop, sec the follow- 
ing possible trouble. 

f. possible trouble: 
improper adjustment of speed droop 

This trouble is recognized by hunting of the engine, 
sluggishness of the governor, that is, inability to cor- 
rect for changes in load quickly, or by observation of 
the speed droop. Speed droop is generally defined in 
terms of percentage. To determine speed droop, the 
throttle is set wide open and full load is applied to the 
engine. The load is gradually reduced to zero with the 
throttle setting unchanged. An accurate tachometer is 
employed in each case to determine engine speed at 
full load and at no load. It will be found that the 
engine speed is lower at full load than at no load. The 
amount by which the two speeds differ is referred to as 
speed droop. Percentage speed droop, usually about 
3 to 4 percent for generator sets, is determined by the 
following formula: 
No load speed — Full load speed 

x 100= % speed droop 

No load speed 

1. Cause and prevention. Improper speed droop ad- 
justment is due to ignorance of adjustment procedures. 
In making the adjustment, care should be taken to fol- 
low the instructions for adjustment. The speed droop 
should always be checked after changing the full 
throttle speed adjustment. 

2. Repair. The speed droop adjustment must be 
made in conjunction with maximum speed adjust- 
ment. Speed droop is changed by changing the effec- 
tive length of adjusting screw B. An increase in the 
length of B between screw A and the rocker lever will 
cause the governor to have more speed droop, and will 
reduce hunting caused by oversensitivity. Shortening 
the effective length of B will cause the governor to 
have less speed droop and will increase its sensitivity. 

It must be kept in mind that a change in speed droop 
adjustment will change the full-load full-throttle 
speed of the engine. If it is desired to set the engine 
full-load full-throttle speed at, for example, 1200 
rpm and the engine no-load full-throttle speed at 
approximately 1240 rpm, the following procedure 
should be employed: 

(a) To decrease speed rise from full load to no load, 
that is, to decrease speed droop, the lever arm B is 
shortened by loosening the right-hand nut C, and 
tightening the left-hand nut C. This adjustment 
should be made by turning the nuts C one turn at a 
time until the proper speed is obtained (see Figure 5-4). 

(b) After each one-turn adjustment, full load is ap- 

Qrigiral from 


plied and speed restored to 1200 rpm by adjusting the 
knurled nut A. The load is then removed and the no- 
load speed is checked to ascertain if it is sufficiently 
close to 1240 rpm. 

(c) To increase speed rise from full load to no load, 
that is, to increase speed droop, the lever arm B is 
lengthened by loosening the left-hand nut H one turn 
and tightening the right-hand nut H. The adjustment 
is then continued as before by restoring full-load speed 
to 1200 rpm by the knurled nut A, reducing load and 
checking no-load speed. 

If speed droop is being adjusted to provide for 
paralleling of the generators, it may now be necessary 
to make electrical adjustments on the generators. The 
manufacturer's instruction book must be consulted for 
the procedure to be used in adjustment of the various 
types of generators. 

g. possible trouble: 
stickiness in governor or external linkage 

This condition almost invariably leads to hunting, 
that is, periodic variation in engine speed at constant 
throttle setting. It can be discovered by working the 
governor parts by hand and noticing any undue fric- 
tion. The external linkage, including fuel control rod 
and pumps, can be checked for excessive friction in 
a like manner. 

1. Causes and prevention. The most frequent causes of 
stickiness in the linkage or of governor parts are: 

(a) Accumulations of dirt in the governor or on 

linkage joints. 

(b) Misalignment of the governor or linkage. 

(c) Distortion of the governor parts or linkage. 

(a) Accumulations of dirt in the governor or on linkage 
joints. If sludge, varnish, paint, or chips are allowed 
to accumulate between the moving parts of the gover- 
nor linkage, excessive wear or friction will result. The 
primary source of governor trouble is dirt. Wash the 
governor and linkage joints frequently in carbon 
tetrachloride, or other clean noncorrosivc solvent, to 
remove all traces of dirt. 

(b) Misalignment of the governor or linkage. If the gov- 
ernor and/or linkage are not properly aligned, binding 
will cause excessive friction and hunting will result. 
When installing the governor and linkage, care should 
be taken to ascertain that the linkage and governor 
are aligned so as to eliminate all bind. 

(c) Distortion of the governor parts or linkage. The bend- 
ing of governor parts or linkage rods and pins, by 
careless handling or improper installation, may readily 
cause roughness and excessive friction, thereby result- 
ing in hunting. The parts should never be forced into 

d • : Go i ilc 

place. All distorted parts should be replaced, or 
straightened if possible. 

2. Repair. The cause of stickiness should be deter- 
mined and eliminated. 

h. possible trouble: 
stripped or worn drive gears 

This trouble may be first noticed by irregularities 
in speed control, causing hunting. The gear train 
which drives the speed measuring element of the gov- 
ernor at a speed proportional to engine speed, must be 
in good condition. Any irregularities in gear profiles 
will result in irregular speed of the governor even 
though the engine speed may be constant. The gover- 
nor, "thinking" that the engine speed is irregular, 
will attempt to stabilize the engine speed by making 
changes in the amount of fuel flow to the engine. This 
will result in change in engine speed and the cycle 
continues. It will be impossible to get rid of this 
hunting without replacing the faulty gears. 

1. Causes and prevention. Worn or stripped drive 
gears may be due to : 

(a) Improper installation. 

(b) Insufficient lubrication. 

(a) Improper installation. In installing the governor 
upon the engine, care must be taken to see that all 
parts are clean. Most governor failures can be traced 
to dirt, and the drive gears are no exception. Before 
the flange bolts that secure the governor to the engine 
are tightened down, a check must be made to see that 
drive gears are properly meshed; otherwise, tightening 
will cause the gears to be marred or broken. Any gear 
showing marked imperfection must be replaced to 
avoid immediate or future trouble. 

(b) Insufficient lubrication. Gears must be lubricated 
properly to prevent undue wear or scuffing. The lubri- 
cating oil lines and passages should be checked for 
stoppage, crimping, or other restriction. The use of 
clean oil is imperative to avoid wear due to abrasive 
action of dirt particles. 

2. Repair. Worn or damaged drive gears must be 
replaced. In most cases it will be advisable to substi- 
tute a spare governor and return the damaged one to a 
repair base. 


5B1. Introduction. The hydraulic governor differs 
from the mechanical governor in that some fluid, 
usually oil, is used to transmit the governing forces 
developed in the governor. It is the most sensitive and 
accurate type of governor and is, therefore, used when- 



ever high precision in speed control is essential. 

The hydraulic and the mechanical governor are 
similar in the respect that both utilize spring loaded 
flyweights to "measure" or "weigh" the engine 
speed. The speed-sensitive (weighing) element in the 
hydraulic governor causes oil under pressure to act on 
a power piston. This piston is connected to the fuel 
pump linkage, and acts to increase or decrease the flow 
of fuel to the engine so as to return the engine speed to 
normal. Figure 5-5 illustrates this principle. 

In most hydraulic governors there is an almost 
simultaneous compensating action. The function of 
the compensating mechanism is to increase the stability 
of the governor, that is, to prevent overshooting, or 
overcorrection of the fuel setting. Compensated gov- 
ernors may be isochronous, which means they are capable 
of maintaining the same speed, or frequency, regard- 
less of the amount of load, up to the load limit of the 
engine. Isochronous governors have no speed droop. 
However, under certain conditions it is advantageous 
to have the speed fall, or droop, as the load is in- 
creased. This characteristic is provided by a speed 
droop mechanism. 

The prime advantage of hydraulic governors is their 
relative freedom from friction. Consequently, gover- 
nor parts are accurately machined. Hydraulic gover- 
nor construction and operation may be compared to 
that of a fine watch. Like an accurate timepiece, the 
governor is sensitive to dirt, and some skill is required 
to adjust it properly. Thoughtless, uninformed tinker- 
ing with the mechanism is not likely to meet with 
much success. 

Personnel associated with the maintenance of Navy 
diesel engines have, in all probability, heard the state- 
ment to the effect that hydraulic governors should be 
left alone. Unfortunately, this has been interpreted 
too frequently as meaning that only experts with long 
experience are qualified to adjust or maintain these 
devices. Hydraulic governors are complicated; they 
have many parts whose function and action are not 
readily understood by an ordinary inspection of the 

mechanism itself. However, a reasonable amount of 
time spent in study of the instructional material avail- 
able will show that the hydraulic governor presents 
no greater problems than those found elsewhere in 
the engine. 

5B2. Sources of information. Among the sources 
of information concerning hydraulic governors are: 

1. That section of the engine instruction manual 
dealing with the governor. Information on simple 
adjustments and, frequently, an explanation of how 
the governor operates will be found there. 

2. Special hydraulic governor maintenance manuals 
prepared by the Bureau of Ships are: Marquette Governor 
Manual , Navships 341-5505; and Woodward Governor 
Manual, Navships 341-5017. These manuals cover 
the most widely used models of hydraulic governors 
and overspeed trips. They contain minute details on 
testing, adjusting, and repairing the governor. Pro- 
cedures for both shipboard and repair base personnel 
are included. 

3. Navy training films on diesel engine hydraulic 
governors. These films, some of the best yet produced, 
contain excellent explanations of the operation of the 
hydraulic governor, and also give worthwhile main- 
tenance hints. 

The following troubles have been encountered with 
a number of hydraulic governors. In the main, they 
are applicable to all hydraulic governors; however, as 
a consequence of the variation in design of different 
models, it has been necessary to include some material 
that is relevant only to certain governor models. 

Dirt is the foremost enemy of successful governor 
operation. Also, the governor cannot be expected to 
control the engine speed unless the governor drive, 
and the linkage between governor and fuel injection 
system, are performing satisfactorily. 

a. possible trouble: 


Governors that have self-contained oil supplies arc 








Digitized by 

Go gle 


Figure 5-5. Operating principle of hydraulic governor. 



designed to operate with the oil at some predeter- 
mined level. If the oil level becomes too low, the 
governor will be unable to control the engine speed 
properly. The engine will hunt, or surge. 

1. Causes and prevention. Low oil level may be due to: 

(a) Failure to follow the instruction manual. 

(b) Leakage of oil from the governor. 

(a) Failure to follow the instruction manual. The en- 
gine instruction manual always specifies the level at 
which oil should be maintained in the governor. This 
level must be maintained for efficient governor 

(b) Leakage of oil from the governor. Generally, an oil 
seal is provided for the drive shaft of the hydraulic 
governor to prevent leakage between this shaft and 
the governor case. An unexplained decrease of the oil 
level may frequently be traced to a faulty condition of 
this seal. For hints on seal maintenance, reference 
should be made to page 115- Leakage at other points 
is usually the result of faulty gaskets between parts of 
the governor case. Prior to installing new gaskets, 
the flange surfaces should be carefully cleaned to re- 
move all traces of old gasket, dirt, etc. 

2. Repair. Low oil level may be remedied by filling 
the governor case to the level specified in the instruc- 
tion manual, with clean oil of the same type as used in 
the engine lubricating system. In cases where the oil 
level recedes frequently, it is advisable to check for 

b. possible trouble: 
stickiness of governor mechanism or linkage 

This trouble is usually the source of hunting or 
sluggishness of the governor. The effect of stickiness 
is most apparent when changes in the load occur. 

For instance, if the load increases, the engine speed 
will drop. The governor flyballs move in, causing oil 
under pressure to be supplied to the power piston. If 
the power piston is sticky, or if the linkage to fuel 
pumps is sticky, considerable pressure may have to be 
built up to overcome the static friction. When the 
static friction is overcome, the linkage is shoved 
vigorously toward the full fuel position. Too much 
fuel is injected and the engine speed rises above nor- 
mal. The governor action then attempts to reduce the 
quantity of injection, and, due to the stickiness, may 
"overshoot" again, this time causing the speed to 
drop below normal. This overshooting is a source 
of hunting. 

Consequently, it is apparent that all moving parts 
in the governor, in the linkage between governor and 

Digitized by GQoQIC 

fuel pumps, and in the fuel pumps themselves, should 
have as little friction, or stickiness as possible. 

1 . Causes and prevention. The causes of stickiness arc : 

(a) Failure to clean the governor. 

(b) Use of dirty governor oil. 

(c) Use of misfit parts in the governor or linkage. 

(d) Binding of the fuel pump mechanism. 

(e) Misalignment of the linkage, governor, or 


(f) Dirt or paint in the linkage joints. 

(a) Failure to clean the governor. This is the most fre- 
quent source of trouble in hydraulic governors. Fail- 
ure to clean the governor at frequent intervals, even 
though clean oil is being used, will cause lacquer-like 
deposits to accumulate on moving surfaces and cause 

The governor should be flushed with clean diesel 
fuel, carbon tetrachloride, or other suitable solvent at 
frequent intervals and when the oil is changed. Most 
governors with a self-contained oil supply can be 
flushed without removal from the engine as follows: 

(1) The oil must be drained and replaced with 


(2) The engine should be run for approximately 

30 seconds with the compensating valve 
wide open, and allowed to surge 

(3) The solvent should then be drained and re- 

placed with clean governor oil. When the 
governor appears to accumulate dirty de- 
posits unusually rapidly, the original oil 
containers should be checked for cleanli- 
ness, and the governor base and other 
parts for sludge layers. 

(b) Use of dirty governor oil. Continued use of dirty 
oil will have the same effect as failure to clean the 
governor. Whenever the governor is flushed, it must 
be refilled with clean oil. The same type oil as used in 
the crankcase should be used for governors with self- 
contained oil supply. Additive type diesel engine 
lubricating oil (9000 Navy series) should be used 
as this will reduce the tendency of deposits to form on 
the governor mechanism, and on other engine parts. 

(c) Use of misfit parts in the governor or linkage. Gover- 
nor or linkage parts that are distorted or scarred 
enough to increase friction or cause binding, must be 
replaced or repaired. Parts should be handled care- 
fully to prevent damage. All parts so badly scarred 
that they cannot be polished without introducing 
looseness or play in the governor or linkage mechan- 
ism, should be replaced. 



(d) Binding of the fuel pump mechanism. If the fuel 
pump parts need cleaning, have been assembled incor- 
rectly, or have been damaged by rough treatment, the 
fuel control rod may be sticky or immovable. In some 
engines this condition will interfere with governing. 
The pump can be checked for stickiness by discon- 
necting the linkage from the pump and trying to move 
the rod manually. Chapter 4, Section 2, gives informa- 
tion on the causes of sticking of fuel injection pumps. 

(e) Misalignment of the governor, linkage, or pump. In 
many cases it will be possible to eliminate stickiness of 
the governor, linkage, or pump by slightly shifting 
the relative position of some of these parts. Where 
clevis type joints are employed, care must be taken to 
see that their alignment is such as to reduce friction to 
a minimum. Always avoid cocking parts or forcing them 
into position. 

(f) Dirt or paint in the linkage joints. Dirt or paint in 
the governor fuel pump linkage joints will introduce 
undesirable friction into the mechanism. When paint- 
ing is done in the vicinity of the engine, the painter 
should be cautioned against allowing paint to get on 
working surfaces. 

2. Repair. To eliminate stickiness, it is first neces- 
sary to determine the parts responsible for the condi- 
tion. This is accomplished most expeditiously by 
disconnecting the linkage from the power cylinder arm 
or rod of the governor, and attempting to move the 
linkage by hand. In engines where heavy springs 
interfere with manual motion of the linkage, it may be 
advisable to disconnect the other end of the linkage, or 
to relieve the restraining springs. By progressively 
disconnecting links, starting at the governor and 
working to the fuel system end, it may be possible to 
determine which part of the linkage is responsible for 
the binding. 

If the linkage does not appear to be the source, the 
fuel pump control rod should be checked for binding. 

Stickiness of the internal governor parts is generally 
difficult to determine without disassembly of the gov- 
ernor. The Bureau of Ships governor maintenance 
manual or engine instruction manual should be con- 
sulted for methods of governor testing. In any event, 
it will probably be advisable to clean the governor. 

c. possible trouble: 


This trouble generally becomes apparent through 
variations in engine speed. The engine may hunt, 
surge, fail to respond to changes in throttle setting, or 
run too fast or too slow. If two engines are being 

Digitizes by COUSIN 

operated in parallel, one may attempt to carry most of 
the load because of improper governor adjustment. 
Smoky exhaust may also indicate improper adjustment. 

Unfortunately, none of these symptoms is a positive 
indication of governor trouble; it is always necessary 
to check the engine to make sure that all cylinders are 
firing properly, that generator characteristics arc 
proper (in the case of parallel operation), and so forth, 
before attributing the trouble to the governor. 

The symptoms usually associated with the need for 
each of the following adjustments will be found under 
the paragraph dealing with the specific adjustment. 
Most hydraulic governors do not have all the follow- 
ing adjustments. It will also be noted that the adjust- 
ment terminology of various governor manufacturers 
differs slightly from that shown. 

1. Causes and prevention. The cause of improper gov- 
ernor adjustment is usually lack of knowledge, on the 
part of the man charged with care of the engine, as to 
the proper adjustment procedure. Maladjustments are 
most frequently made on: 

(a) Speeder spring. 

(b) Compensating needle valve. 

(c) Compensating spring. 

(d) Pump gear end clearance. 

(e) Speed limit. 

(f) Load limit. 

(g) Speed droop. 

(h) Torque limit or BMEP limiter. 

(a) Speeder spring. Variation in governed engine 
speed is accomplished by changing the compression of 
the speeder spring. On constant speed installations, 
the speed may be adjusted by a screw. Variable speed 
installations usually utilize a governor with an exter- 
nal knob or lever, or remote control of the speeder 
spring compression. This is the simplest of all adjust- 
ments and is, therefore, not usually a source of trouble. 
Where remote control is effected by an electrical trans- 
mitter motor, or pneumatic or hydraulic mechanism, 
trouble with these devices may prevent the operator 
from being able to raise or lower engine speed as de- 
sired by operation of thecontrol lever, button, knob, etc. 

(b) Compensating needle valve. Adjustment of the com- 
pensating needle valve is one of the simplest, yet most 
critical, of all adjustments. This adjustment deter- 
mines the speed of action of the compensating mech- 
anism. The adjustment mechanism is usually quite 
accessible, and the adjustment is made while the en- 
gine is running. Sluggishness (slowness of the gover- 
nor to return the engine to the operating speed after 
load changes), or hunting (rhythmic variation of 
speed, first high then low, after load change or con- 

' Origiral from 



tinuously) may indicate the need for needle valve 
adjustment. With proper compensation, the engine 
speed should become stabilized within about 5 or 6 
seconds after a change in engine load. 
The adjustment is made as follows: 

(1) One needle valve should be closed completely if 
two are provided. Two are sometimes provided to 
insure accessibility of the one to be used. 

(2) The other needle valve should be opened about 
one turn, or until the engine surges freely. 

(3) When the engine has surged for about 30 seconds, 
the needle valve should be closed by turning it clock- 
wise until the surging is barely eliminated. The needle 
valve is left as far open as possible to avoid sluggish- 
ness; this will usually be about 34 to % of a turn open. 

This adjustment will be necessary if the governor oil 
viscosity has been changed by replacement or tempera- 
ture change, or if the governor has been reconditioned 
or cleaned. 

(c) Compensating spring. The compensating spring 
acts to prevent overcorrection by the governor. In 
some hydraulic governors, it is necessary to adjust the 
compensating spring compression or length. Improper 
adjustment, in such cases, may introduce play into the 
mechanism. In other governors, it is not possible to 
make any adjustment and it is necessary only to check 
the free length of the spring against the free length of 
a new spring. Improper adjustment, or need for re- 
placement of the compensating spring, may be indi- 
cated by speed fluctuation, hunting, or surging. The 
governor oil level should be checked, and the 
governor should be flushed before suspecting the com- 
pensating spring. The spring or its adjustment should 
be checked as specified in the Bureau of Ships governor 
maintenance manuals. 

A mistake commonly made is to attempt to restore 
the spring to its original length by stretching it. When 
the stretched spring is replaced, it quickly resumes its 
compressed length. It is always advisable to obtain a 
supply of these simple springs so that replacement may 
be made readily. 

(d) Pumf gear end clearance. Most hydraulic gover- 
nors have integral gear type oil pumps to furnish the 
pressure necessary for governor operation. In gover- 
nors where the gear end clearance may be adjusted, it 
is essential that the clearance be proper. Too much 
clearance will allow excessive leakage, reducing pump 
capacity and possibly causing the governor to be slug- 
gish in responding to increase in load. Too little 
clearance will result in contact between the gear and 
the base, with consequent wear. Scoring of the base 

by the pump drive gear will be evident in such ca^es 
when the governor is disassembled. If binding is ob- 
served when an attempt is made to rotate the flyballs 
while the governor is disengaged from the engine, the 
pump drive gear clearance may be insufficient. The 
Bureau of Ships governor maintenance manual should 
be consul ted for further information on this adjustment. 

(e) Speed limit. Most variable speed governors have 
an adjustment that limits the degree to which the 
speeder spring can be compressed. This adjustment 
consequently limits the maximum governed speed 
normally attainable by the engine. If the operator 
finds that the engine speed is too high or too low at 
full speed throttle setting, it is possible that this ad- 
justment may be necessary. Prior to attempting this 
adjustment, the operator must determine that the high 
or low speed is not due to inaccuracy of the tachometer, 
malfunction of other engine parts, or improper adjust- 
ment of the fuel linkage. 

(f) Load limit. Certain governors are equipped with 
an adjustment that limits the maximum travel of the 
power piston rod or lever. Thus, assuming that fuel 
control linkage adjustment has been properly made, 
the load-limit adjustment limits the maximum quan- 
tity of fuel that the governor may demand from the 
engine. If the engine smokes under the load, it is 
probable that the quantity of fuel allowable, that is, 
the load limit should be decreased. If it is impossible 
to attain rated load, and all other parts of the engine 
are functioning properly, the load limit may need to 
be increased. This adjustment should never be made 
unless it is known definitely that it is necessary, as it 
is normally a factory adjustment. 

(g) Speed droop. Speed droop is that property of a 
governor that causes a decrease in governed speed, 
with constant throttle setting, whenever there is an 
increase in the load on the engine. All mechanical 
governors possess the property of speed droop. Hy- 
draulic governors are isochronous (without speed 
droop) or fitted with a mechanism to introduce 
speed droop. 

Speed droop is necessary on governors used to con- 
trol engines driving a.c. generators in parallel, and 
engines in tandem or geared together. Failure of two 
interconnected engines to split the load in the desired 
proportion is frequently an indication that the speed 
droop adjustment on one or both governors is improper. 

The minimum speed droop setting consistent with 
desired operational characteristics should be used. 

If it is desired that two engines in parallel operation 
divide the load exactly, the speed droop on each gover- 
nor should be the same. If it is not, the engine with the 

Digitize; b> GOOQle Original from 



least amount of speed droop will have a tendency 
to assume the greater part of the load. 

Generally speaking, speed droop will be in the 
neighborhood of 6 to 8 percent for most applications. 
The percentage speed droop is generally computed by 
the following: 

, . No-load speed-Full-load speed X 100 

Percent speed droops — — -- — , 

No-load speed 

Full-load speed is the rated speed of the engine under 
full (rated) load condition. 

No-load speed is determined by operating the engine 
at rated speed and load and then, without altering the 
throttle setting, dropping the load from the engine. 

Speed droop should be adjusted as specified in the 
instruction manual. Care should be taken not to 

(h) Torque limit or BMEP limiter. The torque 
(BMEP) limiting feature is sometimes provided in 
governors as an added safety device. This feature pre- 
vents the engine from assuming too much load at low 
speeds, which would cause lugging, overheating, and 
possible overstressing of engine parts. It also prevents 
smoking that results from injection of more fuel than 
the engine is able to burn at any given speed. 

The torque (BMEP) limit control allows no more 
than a certain definite amount of fuel to be injected at 
any given speed. When the engine becomes over- 
loaded, the governor prevents more fuel from being 
supplied. The engine speed drops below normal and 
the engine may hunt, warning the operator to remove 
the load or increase the throttle setting. At increased 
engine speeds, more fuel can be burned safely because 
of lower bearing pressures on the power stroke, higher 
blower efficiency, and increased cooling. 

It is apparent that this feature differs from the 
load limit adjustment in that the latter provides full 
protection only at maximum engine speed. The torque 
or BMEP limiter automatically sets a different load 
limit for every speed of the engine. 

When attempting to parallel two engines, it is 
advisable to see that the two governors have the same 
torque limit adjustments. 

It should not be possible to make an engine in good 
condition smoke if the torque limit adjustment has 
been made properly. 

2. Repair. All adjustments should be made in ac- 
cordance with the engine instruction manual, or the 
Bureau of Ships governor maintenance manuals. The 
ill effects of foolhardy, uninformed tinkering with the 
governor cannot be overemphasized. Certain adjust- 
ments such as those for speed limit, torque or BMEP 
limit, and load limit may cause serious engine damage 

Digitized by 

Go gle 


or injury of personnel if improperly made. The opera- 
tor must be fully informed before attempting to make 
these adjustments. 

d. possible trouble: 
damaged drive shaft 

The fly balls and the hydraulic pressure pump of 
most hydraulic governors are rotated by the governor 
drive shaft. One end of this shaft is splined, serrated 
or keyed to a drive gear, or a mating driving shaft in 
the engine. On numerous occasions the governor shaft 
has failed because of breakage of the shaft or casualty 
to the shaft serrations. 

A review of hydraulic governor theory will reveal 
that if the flyballs cease to rotate, the action of the 
speeder spring will be to increase the flow of fuel to 
the engine cylinders. However, most hydraulic gov- 
erning systems arc so designed that a failure of oil 
pressure, such as might be occasioned by breakage of 
the pump drive shaft, will cause the engine to cease 
operating immediately. In other systems the engine 
may be shut down by the overspeed trip when the 
governor fails. 

1. Causes and prevention. Damage to drive shafts or 
other elements of the governor's drive mechanism may 
be due to: 

(a) Operation without properly functioning 

flexible dampener coupling. 

(b) Poor condition of the drive shaft bearings. 

(c) Failure to inspect serrations. 

(d) Insufficient pump gear end clearance. 

(e) Misalignment of the governor to the engine. 

(a) Operation without properly functioning flexible 
dampener coupling. Many hydraulic governors employ 
a spring type or rubber type coupling in the drive shaft 
to reduce transmission of shock impulses to the 
governor mechanism. If this coupling is not func- 
tioning properly as a result of breakage of springs, 
failure of rubber material, etc., there will be no 
cushioning or dampening effect. This may cause shock 
loads to be transmitted to the governor mechanism. 
Breakage of parts other than the drive mechanism may 
result. A far more prevalent result of this condition is 
the transmission of impulses to the speed sensitive 
element, causing hunting, chattering of power piston, 
etc. The coupling should be maintained by carefully 
inspecting the spring or other cushioning material for 
signs of wear, cracks, disintegration, and the like. 
New parts should be installed if comparison with 
parts in use indicates poor condition of the latter. 

(b) Poor condition of drive shaft bearings. If ball bear- 

Qrigiral from 


^n, it is advisable to install the %p*rc . 

i*g&, m geticrui use io governors, arc insetted or totted, or worn 

maintained m a Airtv condition, the? mar ftetse c,r govcrnur to avo 

cause so much friction that the drive . shiifv - m.;jy be ..(d) Imuffimm - 'pump . g<ter tgrf clearance;. In . certain; 

f s shiitild Hr Misriilled £«:wefmirs ("see Figure "'V--7S. the tiunm pear end clear- 

-r- ■■~T' PUSH R0 ° 



: - : 










* £. ... 


> > 





I :.:v-. 1 • 


;.: -i-.V."'.-' 




e. possible trouble: 
drive gear clearance improper 

The governor is geared to run at a speed consider- 
ably higher than, but always proportional to, that of 
the engine crankshaft. For efficient governing, the 
speed of rotation of the flyweights must accurately 
reflect the speed of the engine. 

Too much clearance in drive gears will cause the 
engine to hunt by allowing the governing element to 
have some motion independent of the engine. 

Too little clearance in some of the gears in the train 
that drives the governor will cause rapid wear and 
may introduce binding into the system. 

It is apparent that imperfections in gear teeth, or 
missing gear teeth, will introduce serious inaccuracies, 
hunting, surging, and so forth, into the governing 

1. Causes and prevention. Improper clearance of drive 
gears may be attributed to: 

(a) Misalignment of the governor to the engine 

during installation. 

(b) Worn or damaged drive gears. 

(a) Misalignment of the governor to the engine during 
installation. If the governor housing is cocked or 
otherwise mispositioned when installed on the engine, 
the gears may be misaligned, causing wear. The hold- 
down bolts should be tightened evenly, making cer- 
tain that the flange faces are clean and the gasket, if 
used, is in good condition. The gear clearance should 
be checked, and if found improper, should be adjusted. 

(b) Worn or damaged drive gears. If drive gears be- 
come stripped, broken, or badly worn, they cannot 
accurately relay the changes in engine speed to the 
governing element. These conditions may be caused 
by poor condition of the shaft bearing, other misalign- 
ment, corrosion, etc. See Chapter 17, Auxiliary Drive 
Mechanisms, for a discussion of gear troubles. 

2. Repair. The drive gear clearance should be 
measured with feeler gage stock, if possible. Other- 
wise, it may be possible to estimate the clearance by 
feeling the play between engine driving gear and gov- 
ernor driven gear. With the governor cover removed, 
it may be possible to turn the flyweight carrier by 
hand. Only enough turning effort to feel the play 
should be exerted . If the flyweight carrier is connected 
to the driven gear by a flexible coupling, sufficient 
force to twist the flexible coupling springs, etc., must 
not be exerted as this will give an erroneous impres- 
sion of the gear clearance. 

The gear clearance is adjusted if necessary by shims, 

replacement of gasket, realignment of governor to 
engine, etc., depending on the installation. If it is 
impossible to adjust clearance properly by these 
means, it is usually advisable to replace the drive gears 
as they are probably excessively worn. Naturally, 
damaged gears must be replaced. If one gear has been 
damaged, it is likely that its mating gear will also 
require replacement. 

When installing the governor on the engine, the 
engine and governor flange faces must be clean, and 
the gasket between them, if employed, must be uni- 
form in thickness and in good condition. As always, 
when tightening flange hold-down bolts, the bolts 
must be tightened progressively and evenly. 

f. possible trouble: 
leaky oil seals 

When it is necessary to add oil too frequently to 
governors with independent oil supplies, the condition 
of the oil seals should be checked. The oil level in the 
governor will subside without any external sign of 
leakage if the oil seal around the drive shaft is leaking. 
Leakage through the oil seal around the power piston 
rod will be visible. 

1. Causes and prevention. The causes of leaky oil 
seals are: 

(a) Improper installation. 

(b) Failure to maintain oil seals in proper 


(c) Overuse of oil seals. 

(d) Failure to clean the governor. 

(a) Improper installation. Great care must be exer- 
cised not to tear or cut the oil seals when installing 
them. The use of sharply pointed instruments should 
be avoided in positioning the oil seals. The proper 
positioning of the oil seal must be made certain, 
because a new oil seal improperly installed may be no 
better than the one it replaced. 

(b) Failure to maintain oil seals in proper condition. Oil 
seals must be stored in such a manner that they do not 
become dry and brittle or dirty. They must be kept 
clean and pliable. 

(c) Overuse of oil seals. This condition is apparent 
when inspection discloses ragged edges or other wear 
that will interfere with proper sealing. 

(d) Failure to clean governor. Sludge and abrasive 
particles will accumulate if the governor is not cleaned . 
This accumulation will accelerate the wear of the oil 
seals. This is only one of the many troubles coincident 
with failure to clean the governor frequently. 

2. Repair. Leaky oil seals must be replaced care- 

Digitized by GOOOle ^ 



fully prior to installation. It is advisable to soak 
leather seals overnight in neatsfoot oil. 

g. possible trouble: 
foaming of governor oil 

The governor oil may occasionally become aerated. 
When this occurs, the oil level increases to such an 
extent that the column is completely filled with foam. 
This. may allow oil to leak out of the governor. 

Extreme aeration may possibly impair governing. 
It may cause more vigorous and continuous correc- 
tive movements of the governor mechanism, and thus 
result in undue wear. It also encourages formation of 
gum and sludge in the governor by increasing the 
opportunity for oxidation. 

1. Causes and prevention. The only cause of foaming 
of governor oil- is filling the governor too full of oil. 
Instruction books invariably specify the correct level 
for governor oil. In some governors, if the oil level is 
increased to the point where the flyball head is par- 
tially covered, the ball arms will act like an egg 
beater in forming an oil-air emulsion. 

Early in the history of additive type lubricating oil, 
this type of oil would foam much more readily than 
other types. By modifying the additive composition, 
this difficulty has been overcome completely. 

2. Repair. Foaming of governor oil may be remedied 
by adjusting the oil level as specified in the engine 
instruction manual. 


5C1. Introduction. Due to the relatively heavy 
construction of parts employed in diesel engines, 
operation at excessive speed is extremely dangerous. 
If the speed is sufficiently high, the engine will fly 
apart due to the high inertia and centrifugal forces 
developed. Whenever the operator is confronted with 
a strange engine, one of the first things he should learn 
about it is some positive method of stopping it quickly 
in an emergency. 

It is best to determine some ready method of chok- 
ing off the engine's air supply. Engines occasionally 
run away because of leakage of lubricating oil into the 
combustion space as a result of leaky blower oil seals, 
broken piping, etc. It is readily seen that an engine 
running on oil from a source other than the fuel injec- 
tion valves cannot he stopped by shutting off the injection 
of fuel. Although the engine can run without diesel 
fuel, it cannot operate without air. In some instances, 
operators have constructed canvas hoods that may be 
quickly slipped over the engine's air intake. 

Digitize- by Google ' 

Another possible method of slowing down a runa- 
way engine is to apply an overload to it. 

In addition to these methods, certain engines have 
compression relief valves, or some mechanism for 
causing intake and/or exhaust valves to remain open, 
acting as compression relief valves. These valves are 
provided primarily to assist the operator in barring 
over or cranking the engine. And in many engines they 
may be used to shut down the engine by releasing com- 
pression within the cylinders. In engines in which it 
is not possible to release compression in all cylinders 
simultaneously, or rapidly, this method is inadvisable. 

5C2. Types of speed governors. All diesel engines 
are equipped with some type of speed governor. A 
number of these governors are equipped with a built- 
in, manually operated, emergency shutdown control. 
Many of these engines are further protected by the pro- 
vision of an additional governing device, overspeed trip 
or overspeed governor, or a built-in manually operated 
emergency shutdown that is independent of the gover- 
nor. These additional devices are provided as a safety 
measure in the event that the normal governor does 
not function properly. The purpose of all such 
devices is to prevent the engine from reaching a dan- 
gerously high speed. This purpose is usually accom- 
plished by shutting off, or at least decreasing, the flow 
of fuel to the engine when its speed tends to become 
excessive. Another less widely used, but highly effec- 
tive, method is to shut off the engine's supply of 
intake air. 

The mechanism for shutting off the fuel supply may 
be arranged to: 

1. Force the fuel control rod of the injection pump 
to the no fuel position. 

2. Block off the fuel line by closing a valve in it. 
3- Relieve the pressure in the fuel injection lines by 

opening a valve. 

4. Prevent the mechanical movement of the injec- 
tion pump by raising the pump's cam followers from 
their cams. 

The mechanism for shutting off the engine's inlet 
air is generally constructed so as to shut off the inlet 
passage to the blower by closing a flap. 

All of the mechanisms described may be actuated 
either manually or automatically, or both. The link- 
age between the actuating device and the shutoff 
device may be either mechanical, hydraulic, electrical, 
or combinations of these. 

Manually operated devices are generally set in mo- 
tion by pushing or pulling a lever, knob, or button. In 
certain installations, the shutdown action will continue 

Original from 



•.•,S < /.,i r v.vV, 

• • • 


1. Causes and prevention. Tripping at a speed below 
that specified in the instruction manual, or modifying 
directive from the Bureau of Ships, is generally the 
result of: 

(a) Improper adjustment. 

(b) Faulty linkage. 

(c) Broken spring. 

(a) Improper adjustment. The instruction manual 
contains information as to the speed at which the 
overspeed trip is supposed to function. Most over- 
speed trips arc adjustable as to tripping speed. It is 
essential that adjustment be made as specified in the 
instruction manual, or as directed by the Bureau of 
Ships in instances where the tripping speed has been 
modified. A possible consequence of adjusting the 
overspeed trip to trip at too low a speed is illustrated 
by the following experience of a small vessel : 

The vessel was engaged in depth-charging an area. 
While running at full speed, it was found that the 
concussion from the charge dropped was sufficient to 
raise the stern, and consequently, a portion of the 
screw out of the water. The engine immediately 
speeded up and was shut down by the overspeed trip, 
leaving the vessel momentarily without power in the 
water. The possible consequences of such an occur- 
rence are readily imagined. This particular vessel was 
fortunate in that no subsequent depth charges had 
been rolled off the stern. 

(b) Faulty linkage. As previously mentioned, link- 
age between the fuel or air system and the speed sensi- 
tive element may be either mechanical, hydraulic, 
electrical, or a combination of these. 

Mechanical linkages should be checked for wear. 

Hydraulic lines should be inspected for signs of 
leakage or crimping. 

Electrical wiring, switches, and solenoids should be 
checked for short circuits or damage to insulation that 
might result in short circuits. 

(c) Broken spring. A broken or weak overspeed trip 
spring will cause the trip to operate below the proper 
speed. Spring breakage may be minimized by inspec- 
tion of the spring for wear or defects when the over- 
speed trip is disassembled. Questionable springs 
always should be replaced. 

2. Repair. This trouble is overcome by correct ad- 
justment of the overspeed trip, by repair or replace- 
ment of the faulty linkage, or by replacement of the 
broken spring. Prior to making any change in the 
adjustment of the overspeed trip, it must be ascer- 
tained that the engine has not stopped for some reason 
other than action of the speed sensitive element of the 

Digitized by 

overspeed trip. It is highly advisable to check the 
accuracy of the tachometer and then test the trip 
for operation. 

Referring to Figure 5-8, it is seen that by screwing 
down on the threaded plug it is possible to increase the 
compression on the spring, thereby preventing the fly- 
weight from flying out until a higher speed is reached. 
The principle of adjustment of most overspeed trips is 
identical to this. 

b. possible trouble: 
trip fails to operate at specified 
tripping speed 

As the overspeed trip is furnished for the protection 
of the crew and engine, it is imperative that it be 
maintained in operable condition at all times. This is 
best accomplished by frequently testing the overspeed 
trip to see that it is operating properly. It is obviously 
highly desirable to recognize failure of the trip to 
operate at specified tripping speed during a test, under 
controlled conditions, rather than in an emergency, 
when such a condition may prove definitely hazardous. 

A convenient method of checking the overspeed 
trip, or any emergency shutdown device, is to use the 
overspeed safety devices occasionally when the engine 
is to be shut down during the normal operating rou- 
tine. When the performance of an overspeed trip is to 
be tested, the procedure must be based on the possi- 
bility that the overspeed trip will not work satisfac- 
torily. That is, the operator must be extremely cau- 
tious not to subject himself to injury by haphazardly 
increasing the engine speed to a dangerous point. In 
most cases, it will be necessary to increase the maxi- 
mum speed setting on the primary engine governor to 
get the engine up to specified tripping speed. Any in- 
crease above rated speed must be made slowly in small 
increments, giving the engine ample time to come up 
to full speed after each change in throttle setting. 

1 . Causes and prevention. Failure of trip to operate at 
specified tripping speed may be the result of: 

(a) Improper adjustment. 

(b) Dirty mechanism. 

(c) Linkage binding. 

(d) Trip drive shaft broken. 

(e) Insufficient oil in the hydraulic trip. 

(a) Improper adjustment. See (a) above, on improper 
adjustment. This material refers to increasing the 
tripping speed by adjustment. It is likewise possible 
to reduce the tripping speed by reducing the compres- 
sion on the spring shown in Figure 5-8. Complete 
directions for adjusting the overspeed trip may be 

Qrigiral from 


found in the engine instruction manual. In addition 
to the spring adjustment, common to many overspeed 
trips, in certain engines the adjustment of linkage, and 
other mechanism outside of the speed sensitive device, 
may require attention. This adjustment is critical; 
instructions for making it may be found in the 
instruction manual. 

(b) Dirty mechanism. Hydraulic overspeed trips are 
extremely sensitive to dirt. Mechanical trips are also, 
but to a lesser degree. Dirt or lacquer-like deposits 
may cause the trip to bind internally. Not only must 
the speed sensitive element be scrupulously clean, but 
attention must be given to maintaining cleanliness in 
all parts of the linkage and mechanism not incorpor- 
ated in the speed sensitive element. 

When painting is done around the engine, the 
painter should be cautioned against allowing paint to 
fall into joints, springs, pins, and other critical points 
in the linkage. 

A thorough cleaning of the entire overspeed trip 
may eliminate improper functioning of the trip. 

(c) Linkage binding. See (b) Faulty linkage, page 
118. All parts of the linkage should be checked for 
freedom of motion. If parts are bent, badly worn, 
improperly positioned, dirty, or if their motion is 

restricted by some other part of the engine or external 
obstruction, the trip will not function properly. Re- 
gardless of the condition of the speed sensitive ele- 
ment, the trip cannot operate satisfactorily if its 
linkage is not in good shape. 

(d) Trip drive shaft broken. On occasion, the drive 
shaft of the overspeed trip has been broken, preventing 
rotation of the flyweights and, consequently, opera- 
tion of the trip. 

(e) Insufficient oil in the hydraulic trip. Although the 
speed sensitive element may function perfectly in the 
hydraulic type overspeed trip, its messages cannot be 
transmitted to the fuel system unless its supply of oil 
is sufficient. The oil level should be maintained as 
specified in the instruction manual. 

2. Repair. The cause of maloperation should be 
determined and eliminated. This will involve clean- 
ing the trip and its linkage, removing a source of 
binding, replacing faulty parts, adding oil to the hy- 
draulic type trip, or adjusting the speed sensitive 
element, in accordance with the instruction manual. 
If the trip has been damaged it is advisable to install 
the spare overspeed trip and return the faulty one to a 
repair base. 

Digitized by G0O 


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6A1. Introduction. The lubricating system of the 
diesel engine is one of the most important systems of 
the entire engine. Failure of the lube oil system will 
invariably cause the engine to seize and cease running. 
Whenever this happens, severe damage to the many 
finished surfaces invariably results. Such damage to 
the engine parts necessitates their removal and replace- 
ment, which is not only expensive but laborious. 

The importance of the system cannot be overstressed, 
nor the need for properly maintaining it. When speak- 
ing of the lube oil system, the following components 
are included: 

1. Pumps. 

2. Heat exchangers. 

3. Valves and pressure regulators. 

4. Passages and piping. 

5. Centrifuges, strainers, filters. 

Lube oil pumps are of the positive displacement 
type. Many of the pumps have pressure regulating or 
pressure relief valves built directly into the pump, 
while others rely on valves exterior to the pump to 
control the pressures maintained by it. Such regu- 
lating devices usually recirculate the excess lube oil 
back through the pump. However some pumps dis- 
charge the excess oil directly into the engine sump. 

The positive displacement pumps used for lube oil 
systems *re of the rotary gear type. This type of 
pump is fully discussed on pages 37-39. The prob- 
lems encountered in gear type pumps are the same 
when pumping lube oil as when pumping fuel oil. 

a. possible trouble: 
lube oil pump failures 

Lube oil pump failures are evidenced by loss of lube 
oil pressure. Many other lube system failures are 
similarly indicated. The loss of lube oil pressure can 
first be recognized or discovered by observing the 

Digitized by 

Go gle 


pressure readings of the pressure gages at the time of 
the regular watch. Most lube oil pump failures do not 
occur abruptly, since the majority are due to wear and 
therefore develop gradually. Failures that occur 
abruptly, such as a broken drive shaft, or damage of 
any kind where the parts suffer physical deformation, 
are usually indicated by the sounding off of the warn- 
ing siren. Each engine is equipped with a special 
warning device that is usually connected with the lube 
system and the cooling water system. This warning 
device notifies the operator whenever the operating 
limits of the engine are not within their proper range. 
Provision is made to test the warning system and it 
should be checked at the beginning of each watch. 
The warning system is connected directly in the lube 
oil pressure lines, and if it is left on while the engine is 
being shut down, the siren will sound off as the speed 
decreases. It is a good policy to take advantage of this 
as an additional means of checking the system. Too 
much faith must not be placed in this warning system, 
however, and its presence in no way diminishes the 
responsibility of the engineering force to keep a vigi- 
lant and accurate watch of the engine instruments. 
The instruments will give the operator a clear under- 
standing of just what the engine is doing and what 
adjustments are necessary, if any. 

1. Causes and prevention. The causes and prevention 
of troubles have been discussed in Chapter 4, pages 
38 39. 

Repair. See Chapter 4, page 39. 


6B1 . Introduction. Oil coolers are used to control 
the temperature of the lube oil that is circulated 
throughout the engine. The oil, as it passes through 
the many oil passages, etc., will absorb heat from the 
metal parts with which it comes into contact. Heat 

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will also be absorbed as a result of the friction of the 
oil as it passes through the many bearings. 

Since the oil is being used over and over, it is con- 
tinually receiving additional heat. If no provision 
were made to remove this heat, the temperature would 
rise to excessive values. At such elevated temperatures, 
the oil tends to oxidize more rapidly, and to form car- 
bon deposits. Excessive temperatures also cause in- 
creased oil consumption rates. Consequently, it is 
necessary to have oil coolers to remove the excess heat 
from the oil. Under stabilized temperature conditions 
of operation, the coolers remove exactly the same 
amount of heat from the oil that the oil picks up as it 
circulates through the engine. 

However, oil that is cold cannot circulate through 
the small passages in sufficient quantities to lubricate 
the bearing surfaces properly. It is, therefore, neces- 
sary to control and limit the amount of cooling. This 
is accomplished by the use of temperature regulating 
control valves, discussed in Chapter 7, pages 150-155. 

The Bureau of Ships has set up operating limits with 
regard to the temperature of the lubricating oil. Since 
it is virtually impossible to regulate the amount of 
temperature rise of the oil within the engine, the only 
specification that can be given is the outlet tempera- 
ture of the oil. The preferred temperature is 165°F, 
and the maximum 180°F. These temperature limits 
must be complied with. The maintenance of the 
proper temperatures is dependent upon the condition 
of the oil coolers. Oil coolers that, due to improper 
maintenance, have excessive scale formation and are 
dirty reduce the efficiency of the unit and when 
severely dirty will prevent the cooler from abstracting 
enough heat to keep the oil within the prescribed limits. 

Coolers must also be oil- and watertight, since any 
leakage between the two sides of the cooler will allow 
mixing of the water and the oil. 

a. possible trouble: 
excess scale on cooler tubes 

The collection of scale and dirt on the cooler tubes 
is a gradual process. The presence of scale and dirt is 
usually indicated by an increase in oil temperature, 
without any change in cooling water temperature, 
when the engine is operating under full load conditions. 
If this condition is serious, it may be accompanied by 
excessive pressure drop across the cooler. However, 
since such pressure drop is usually small, it should not 
be relied upon as an indication of trouble. 

1. Causes and prevention. Presence of excess scale 
on the cooler tubes may result from the following: 

Digitized by GQoQIC 

(a) Normal use. 

(b) Improper maintenance of zinc plugs and 


(a) Normal use. The majority of the scale and de- 
posits on the water side of the cooler are not prevent- 
able as they are caused by normal operation. Timely 
removal of the deposits will reduce to a minimum the 
damage and operational difficulties they cause. 

The cooler should be inspected for excessive scale 
formation at 30- to 60-day intervals. This can usually 
be accomplished by removing the inspection plates, or 
the covers, that support the zinc plugs. If the scale is 
excessive, it should be removed as directed in the fol- 
lowing paragraph under 2. Repair. 

(b) Improper maintenance of%inc plugs and plates. When 
sea water is the cooling medium, zinc plugs or plates 
are inserted in the cooler to counteract the electrolytic 
action between the dissimilar metals. The zinc plugs 
or plates, or zincs as they are often called, must be 
inspected at 30-day intervals. At that time, they must 
be thoroughly cleaned. This can be accomplished 
easily with a steel brush. 

Failure to maintain the zincs properly will allow 
the white powdery formation to become excessive, 
often resulting in the reversal of the electrolytic action, 
which will cause severe deterioration of the cooler. 

When the zinc plugs or plates are 50 percent or more 
disintegrated, they must be replaced. 

2. Repair. There are two general types of lube oil 
coolers : shell-and-tube type with cylindrical tubes; and 
Harrison type with flat tubes or elements. In the shell- 
and-tube type, the cooling water passes through the 
tubes while the path of the oil is around and between 
the tubes. On the other hand, oil goes through the 
tubes or elements of the Harrison cooler and the cool- 
ing water passes over the outside of these elements. 

Since the two types of coolers are different in con- 
struction, different procedures are required for cleaning 
and repair. 

(a) Shell-and-tube coolers. The sea-water passages of 
this type of cooler can be cleaned readily by passing an 
air or water lance completely through each tube. In 
some cases, it may be necessary to supplement this bo- 
using a round bristle brush, or by passing soft rubber 
plugs through the tubes. In no case should a wire 
brush or rubber plugs having metal scrapers attached 
be used. These tools will remove some of the protec- 
tive coating formed on the tubes and cause local attack 
on the tubes with resultant early tube failure. This 
cleaning will be much more effective as well as more 

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Ions of pyridine to each gallon of muriatic acid. 
(.002 gallons is 34 ounce.) 

Tank No. 2 is rilled with cold water, and in tank 
No. 3 a 5 percent solution of sodium carbonate is pre- 
pared. A 5 percent solution by weight is roughly half 
a pound of sodium carbonate for each gallon of water. 

The heat exchanger unit is disassembled, the core 
being removed from the case when practicable, to 
facilitate access to the parts. The unit to be cleaned is 
supported by a wire and submerged in tank No. 1, 
which contains the acid solution. Foaming will start 
immediately, and continue as long as the cleansing 
action is taking place. As soon as the foaming ceases, 
the unit should be removed from tank No. 1, and 
placed for about one minute in tank No. 2, which con- 
tains the cold water. The unit is then removed from 
the second tank and immediately immersed in tank 
No. 3- If all the acid was not removed in the second 
tank, there will be a bubbling action when the core is 
inserted in the third tank. If the bubbling persists, the 
core should be allowed to remain in the third tank 
until the bubbling ceases. It is then removed and 
flushed with a hose connected to a fresh warm water 
supply, or if warm water is not available, to a cold 
fresh water supply. 

The procedure can be duplicated with the case and 
covers to remove any deposits from them. 

b. possible trouble: 
leakage of oil tubes 

The leakage of oil tubes is serious. If the water 
pressure is greater than the lube oil pressure within 
the cooler, the lube oil will become contaminated. 
Lube oil containing water is a poor lubricant and will 
ruin the engine bearing surfaces in a short time. The 
water also causes a corrosive action on the bearing 
metals and other engine parts. Leakage of the water 
into the lube oil is found by regular periodic inspec- 
tions of the lube oil for the presence of water. Another 
indication would be the apparent increase in the vol- 
ume of lube oil in the engine sump. 

If the lube oil pressure is greater than the cooling 
water pressure, the oil will leak and escape into the 
cooling water. This type of leak is discovered by 
the presence of oil slicks in the cooling water. If 
the coolant is sea water, it is discharged overboard. 
If the oil is cooled with fresh water, the most desir- 
able method, the oil will first be apparent in the 
expansion tank, and if the oil leakage is large, the 
expansion tank is liable to overflow. 

Another indication of oil leakage is the loss of oil 
from the sump without other apparent causes of the 

Digitizes by GOuQle 

leakage. In this case, where the lube oil pressure is 
greater than the water pressure, when the engine is 
operating, water is apt to enter into the lube oil when 
the engine is shut down. Often when the engine is 
shut down, the greater pressure of the water, due to 
its hydrostatic head being greater than that of the lube 
oil, will cause the water to leak into the oil side of the 
cooler and then find its way to the lube oil sump. For 
this reason, it is imperative that the engineer force 
check the lube oil for water before starting the engine each 
time it has remained idle for a period of three hours or longer. 

If the cooler is thought to be leaking, a positive 
check can be made by removing it from the engine, 
plugging the outlet of the cooling water side, and at- 
taching a low-pressure air hose to the inlet. A pressure 
gage should be included in this system to determine 
the pressure within the unit when testing. Both the 
inlet and outlet openings of the oil side of the cooler 
should be left open. The design pressure as given on 
the name plate should be checked. With the cooler 
submerged in a tank of fresh water, air is admitted to 
the water side, care being taken not to exceed the 
pressure specified on the name plate. Should there be 
any leaks, air bubbles will be seen escaping from 
the cooler. 

Causes and prevention. Leakage of oil tubes iscaused by: 

(a) Erosion. 

(b) Electrolytic action. 

(a) Erosion. The cause of most leaks is erosion of the 
tubes or core on the water side. Water, and particu- 
larly sea water, has a great erosive action on metal 
when the velocity exceeds six feet per second. 

To minimize erosion, the velocity of the water must 
be kept at or below a velocity of six feet per second. 
When the cooler becomes covered with scale and the 
oil side of the cooler needs cleaning, it is usually very 
difficult to maintain the temperature limits of the lube 
oil. Generally the first thing that the operator does is 
to increase the flow of the cooling water, thereby 
increasing the velocity of the water over the tubes and 
increasing the erosion by the action of the water. 

Tests have shown that the greatest problem in 
transferring the heat from the lube oil to the cooling 
water is on the oil side, getting the heat from the oil 
to the tube wall, rather than through the tube wall 
and into the cooling water. Under the usual condi- 
tions, it is approximately ten times as difficult to 
transfer the heat from the oil to the tube wall as it is to 
transfer the heat from the tube wall to the cooling 

Since the heat transfer difficulty is on the oil side, 
the effects of increasing the water velocity arc small. 


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Digitized by 




.^UBLK*: om f?e renewed, arid 

fr fewfr V*tVE (cVATfe VALVES) fete^*!. 

7~ ~~ ~ , 1* ^ adv.bjrJt «ot co jrrempc to repair gatfc valves 


2. Repair. Stuffing box leaks can usually be stopped, 
if the valve stem is in good condition, by setting up on 
the gland. If this does not stop the leakage, it will be 
necessary to repack the stuffing box. 

Should the stem be bent or scored, it will first be 
necessary to straighten it. 

If the packing is old and deteriorated, it must be 
replaced. Packing is supplied in three forms: 

(a) String type. The packing is in a continuous roll, 
usually of a square cross-section. 

(b) Ready formed washer type, usually split to 
allow it to slip over the stem. 

(c) Putty-like compound. 

Type (a) is by far the most common packing used. 
The gland is packed by passing successive turns of 
packing in the space around the rod or valve stem. 
When putting in string packing, it must be wound in 
the same direction as the threads on the nut; that is, if 
the packing nut is turned to the right (clockwise) to 
be tightened, the string packing must also be installed 
clockwise. If the nut is left-handed, the packing must 
be installed in a counterclockwise direction. The ends 
of the packing should be cut on a bevel to lessen the 
likelihood of leakage. 

Type (b) packing is also frequently used. If it is 
necessary to cut the rings in order to place them on a 
shaft, the cut must be made at an angle to produce a 
beveled joint. Thus, the pressure of the nut tends to 
seal the joint, preventing leakage. 

6C3. Check valves. Check valves are valves used 
to allow the fluid within a line to flow in one direction 
only. The majority of check valves are actuated by a 
light spring that seats the valve when the flow ceases. 
With the check valve seated, it is impossible for the 
fluid to back up, or to drain. 

a. possible trouble: 


1. Cause and prevention. Leakage is caused by a 
pitted valve or valve seat. Such pitting usually results 
from abrasives becoming caught beneath the valve. 

2. Repair. If the check valve is a ball, it will be 
necessary to replace it and to refinish the seat. If it is 
a flat or conical check valve, it will usually be possible 
to repair the damaged surface by lapping the surfaces 
together with a fine lapping compound. 

When installing or replacing check valves, it must 
be remembered that the fluid will flow through them 
in only one direction. Be sure that they are installed 

Digitized by GQoQlC 

6C4. Pressure regulating valves. Pressure regu- 
lating valves are required in a lube system in order to 
maintain an even lube oil pressure as the engine speed 
changes. All lube oil pumps are of the positive dis- 
placement type; therefore it is essential that excess oil 
be afforded some means of escape in order to prevent 
extremely high pressures in the lines and at the bearings. 

a. possible trouble: 
defective pressure regulating valve 

Defective pressure regulating valves are evidenced 
by low and erratic lube oil pressures, and are most 
noticeable when the lube oil temperature is high. 
There are many other factors that will cause the same 
symptoms, such as a clogged filter or cooler, worn oil 
pump, loose bearings, low oil level, high oil tempera- 
tures, lube oil dilution, and lube oil leaks. 

1. Causes and prevention. 

(a) Loose lock nut. 

(b) Scored valve. 

(c) Broken spring. 

(d) Sluggish valve. 

(a) Loose lock nut. If the adjusting screw lock nut 
becomes loose, it will allow the adjusting screw to 
back off, thus decreasing the tension in the spring and 
the load on the valve. 

(b) Scored valve. Scored and pitted valves and valve 
seats will cause poor pressure control. When the seat 
and valve become badly pitted, the operation of the 
valve will often be irregular, sometimes maintaining 
the normal pressure and at other times allowing it to 
fall below the required pressure. 

(c) Broken spring. A broken valve spring will cause 
the pressure to drop, as the valve will be loaded with, 
at best, a smaller force. 

(d) Sluggish valve. Should the assembly become 
gummed due either to the oil or foreign particles in 
the oil, the valve will probably hang open, thus offer- 
ing no restriction to the amount of oil bypassed. This 
effect will be more noticeable at the lower speeds. 

2. Repair. Most pressure regulating valve failures 
are due to wear. For this reason, the engineer force 
must keep a record of the rate of wear on the valves 
and replace them when necessary. 

Gum and resinous deposits should be removed from 
the valve with Carbon and Lacquer Removing Com- 
pound (Fed. Std. Stock Cat. No. 51C-1567-56). The 
valve can be cleaned further by lapping with rouge. 

6C5. Temperature regulating valves. Temperature 
regulating valves are used to control the temperature 

Drigiral frcrn 


of the lube oil. They regulate the flow of water through 
the lube oil cooler. 

Regulating valves are thoroughly discussed on 
pages 150-155. 


6D1. Cleanliness. It is absolutely necessary that 
all lube oil passages be kept clean and unrestricted to 
insure a sufficient quantity of lubricant to the moving 

a. possible trouble: 
plugged lube oil lines 

Clogged passages may be indicated by increased oil 
pressure gage readings. However, to rely on such a 
means would be dangerous. If a stoppage should be 
located beyond the pressure regulating valve and also 
beyond the pressure gage, it is very doubtful that any 
pressure increase would be perceptible on the gage. 
The best way to ascertain whether or not a bearing is 
receiving oil, is to inspect it occasionally, just after 
the engine is shut down. It should be made certain 
that an abundance of oil is in the vicinity of the parts 
being lubricated. Another good check for bearing 
lubrication is to note the temperatures of the bearings 
after the engine has been shut down by feeling them 
with the hand. The operator should be able to keep 
his hand on them for only a few seconds. 

1. Cause and prevention. The cause of plugged lube 
oil lines is carelessness. Lube oil lines are not often 
found plugged. When they are plugged, it is due in 
most cases to dirt or other foreign matter that has been 
left in the engine through the carelessness of the crew 
when making repairs and routine inspections. 

Most oil line stoppages can be prevented by careful 
operation and observing a few rules of cleanliness: 

(a) Cotton waste should never be used about a diesel 
engine for cleaning purposes. 

(b) Paper towels should never be used, as they leave 
lint. Small bits are apt to be torn off which later may 
collect in the piping, etc. 

(c) Oil filters should be serviced at specified inter- 
vals. (See page 135 ) The filter case must be cleaned 
properly. Whenever the oil lines are removed, they 
should be blown out with compressed air. 

2. Repair. If any restrictions or dirt are found in 
passages, a stiff wire should be run through them, 
followed by flushing with a light oil, such as diesel 
fuel. They should always be blown out again with 
compressed air. 

Digitized by GOuQIC 

B. POSSIBLE trouble: 

Cracked lube oil lines are difficult to locate if they 
are within the engine, unless a careful inspection is 
made of each individual line. Cracked lines on the 
exterior of the engine are readily detected by the ex- 
cess oil on the piping itself, and on the surrounding 

1. Causes and prevention. Improper support is the 
most frequent cause of cracking. Lube oil line cracks 
are most often caused by vibration of the lines them- 
selves. Rarely is the crack due to excessive pressure. 
Light tubing and piping must be supported adequate! y 
at points along its length. If a pipe line or tubing is 
securely fastened at two places, and the two supports 
have relative motion such as vibration between them, 
trouble with cracking lines will be reduced or elim- 
inated. Once a crack has started, it usually spreads 
very quickly. 

2. Repair. Cracked lube oil lines should be replaced, 
if new ones are on hand, or if they can be obtained. 
When new lines are not available, repairs to the old 
lines must be made. Cracks at the ends of the line, 
such as at the base of the flare, can be repaired by form- 
ing a new flare. The extra material to form the new 
flare can usually be gained by rearranging the tubing 
or by eliminating all slack. 

If the line is made of copper tubing, the entire 
length of it should be fully annealed before any at- 
tempts are made to bend it or to put a new flare on 
the end. 

Copper is annealed by bringing it up to a dull red 
heat and then quenching it in water. 

When forming new flares, it is safer to form them in 
two or three steps, annealing the tubing between each 
step. The life of the flare will also be greatly increased 
if it is annealed after the flare is completed. 

If cracks occur along the line away from the ends, 
the type of repair will be very different. In the usual 
case, it will be necessary to form some sort of splice. 
To do this, a short piece of tubing is needed, of a 
diameter slightly greater than that which is being 
repaired, to act as a sleeve (see Figure 6-10). 

If the crack is not complete, it will be necessary to 
cut the tubing at the crack with a hack saw. The 
tubing should now be cleaned out thoroughly, first 
with a solvent such as gasoline or kerosene, and then 
flushed through with carbon tetrachloride. The sur- 
faces should then be cleaned thoroughly either by 
scraping or light filing. Before assembling the tube, 

Original from 


m i §*i |.h ««. .«* .s ^ ********* ***** 4^ 


rhc ends should be coated v 

j>5cmbicd with the short sleeve, heated thoroughly. proper 1 

daro, or 


4 nd solder is Applied freely- The solder should run una d a 
ch* jomt and fiutc;* perfaci >e.ii cu 

in the -centrifuge for oil of the parncubr density chat 

Oil passm* over with the water indicates thar a 

Qh tfed rubiri^, eta wrtic process t«% he used, but governed by the relative density of ch/? ml and the 

l( i'.v. •' • ' .' ••" >■■'■' . ' *' ' '. '. ' . - i . *- ....'» . i 1' -i !•>»*■ . Meruit! fVi f ,r*/^ii«t*/« i r»«rth- .-inrtV «5 fit ■rf^rV* unrto 

i ...Jics. dogged it: wilt prevent separation of the oil 
E. CENTRIFUGES.. STRAINERS, FILTERS and water The bowi or sptnuk must be cleaned rcgn ■ 

6E% Introduction. One of the mot important re- larlv 35 <wu,,,,cd in t,iC infraction- manual. 

>e operation can be oh- 
- manual exactly 
ring or dam in- 
:er sea) formed befom ajymcting 


i ! •;•*...;.•• / .V: ;. ", . ,;•♦..•;»,; t ■ 

[ ••'- •. 4 

:^ *'V 3 ? BBS 

lube oil system imnicdiateiv- following the 
punjp. The strainers generally are of the wire 
or of ihz jaaai edge tvpe, which are self-cleaned by 
Vor;a dog a ^pecliil scrapiiig device within the filter 

Tht foreign material trapped Kv the strainer will 
drop to the ■ bottom of the case and collect there, it ^ 

|gs 1 
• 2L - 

lr<. - ; 

b) Future so frftin fiittr edit Failure to drain' the 
filter case at specified intervals will allow the uiudgfc . 
ffa«f. .W«f»W »(7 W.r level to increase, and therefore to plug the lower part 

of dhe filter dement 
" w safeguard the bearings, 'All filters art eoni ofied with drain c«* 


900 to 1400 hp 6 elements 

] 400 to 2000 hp 8 elements 

(e) Carelessness. Carelessness is responsible for much 
of the dirr found in the lube system of the average 
engine. Much dirt is admitted to the engine crank- 
case, and eventually washed into the sump, when the 
engine is being worked on. This dirt is brought in on 
shoes, tools, parts, rags, and so forth. It is most im- 
portant that every care be taken to keep the engine 
clean. The engine must never be left uncovered during 
overhaul periods, as dust and dirt will settle on the 
many engine parts. 

2. Repair. The filter elements must be replaced 
whenever they are clogged, regardless of whether or 
not the allowed number of engine hours have elapsed. 

When replacing filter elements, the following pre- 
cautions must be observed: 

(a) The case must be flushed thoroughly to remove all 
traces of dirt. 

(b) The new element must be positioned correctly. 

(c) All cover gaskets must be replaced if new ones 
are available. 

If the filter elements are plugged and no new ones 
available, it is possible to clean them partially by the 
same method outlined for fuel oil filters on pages 93-94. 

Digitized by GOOSES 





7A1. Introduction. The cooling system is pro- 
vided to keep engine parts and working fluids at safe 
operating temperatures. 

If the metal parts, such as liners, pistons, and valves, 
arc allowed to overheat, the tensile strength will be 
materially reduced, thereby accelerating wear and 
increasing the probability of failure. If overheating is 
sufficiently severe, the part will melt. Furthermore, 
overheating may cause undue expansion with resultant 
reduction of clearances between the working parts. 
The latter condition may result in seizure of such parts. 

Lubricating oil picks up heat from combustion, and 
also from friction in the bearings. This heat must be 
removed to retard oxidation of the oil and consequent 
sludging. Overheating of lubricating oil will also 
cause a reduction in viscosity, or thinning, of the oil 
that may permit rupture of the oil film. 

Some supercharged engines have air coolers down- 
stream of the blower to reduce the volume of a given 
weight of air, thereby allowing more pounds of air to 
be taken into the cylinder. 

The cuantity of heat removed from a diesel engine 
by the cooling system is usually approximately equal 
to the quantity of heat that is transformed into useful 
work by the engine. 

In marine installations, most of the engine parts and 
lubricating oil are cooled by circulation of sea water 
and fresh water, or both. Antifreeze is sometimes sub- 
stituted in cold climates. In certain engines cooling 
of the pistons is largely accomplished by spraying or 
circulating oil inside them. This oil is subsequently 
cooled by circulation through an oil cooler. 

In the open type cooling system, only sea water is 
circulated through the engine cooling jackets and oil 

In the more modern closed cooling system, only 
fresh water (or antifreeze) is circulated through the 

Digitized by GQoQIC 

engine cooling jackets. The fresh water is subse- 
quently cooled by sea water in a heat exchanger. Oil 
may be cooled either by fresh water or by sea water. 

Engine jacket water temperatures must be main- 
tained high enough to hinder the condensation of 
corrosive gases on the cylinder walls. The lowering of 
the jacket temperatures to the point where ignition 
lag is increased, which will cause detonation, or 
rough running, must also be prevented. 

The jacket water temperatures must be maintained 
low enough to prevent formation of steam pockets in 
isolated spots. These so-called local hot spots cannot be 
cooled adequately because of the absence of the proper 
quantity of coolant. 

Consequently, much attention muse be given to 
maintaining engine cooling water temperatures within 
the limits specified by the engine manufacturer. Varia- 
tion from specified temperatures is an indication of 
impending trouble. 

The major problems encountered are: maintenance 
of circulating pumps in operable condition; prevention 
of corrosion; reduction of tendency of scale to form in 
the jackets and heat exchangers; proper cleaning pro- 
cedure for jackets and heat exchangers; and prevention 
of leaks in various parts of the system. 

The operator of a particular engine should study its 
cooling system flow diagram, and become familiar 
with the various components of the system. An at- 
tempt should be made to visualize the probable exter- 
nal indications of future trouble. 


7B1. General. There are two types of heat ex- 
changer in general use by the Navy. These types arc: 

1. Harrison type. 

2. Shell-and-tube type. 

Heat exchangers are devices used to cool one fluid 
by transferring the heat to another fluid. The two 

Original from 




fluids are prevent^ from mixing by the thin wall of. a. -giog ?s indicated by a gradual incrcaie in rhe pressure . 

tube itr other eJemcnr 'Elements .vr.arv consi Jcr-^biy hi ^tference between' ihc i<t!ci Mid outlet of cbc cooler . 

>hape-, ^cof^ing to d^ign.. Figure 7^1 shows (he two A* tb* amount of scule increases, dbwr quajtttry of sea 

iivicccssibiht v of rhi- rfibe* prevents the use of-'mcchatt- 
>cal methods IV frc^ueiKV of dealing cjq be re- . 

precaution^ such as matnrainmg proper teinptr;uurei« 
COUcmlKng (act<(iry Of a!kAHnity>, ett 
. ; (b) Operation ti>iih > vlzvafed ita>-w#tet nmptt<*t*irz. The 

: v sca-wuter di.sch.irgc tender aturc must be mawajoed 

^^pJl''' hctavv ] 50 C, F. Ac higher faupemurts, the rare of' <icale 

I mm mm 


• ~ difficult, w remove. Ri 
discussed on p^gc 138. 

Coolw tifcmems may become cfqgged with such 
irurerral as marine Hfe, greascyqr sand: Such -dodging pfflj 
greatly f^*^ = •■■■■-■ ■ * ■ • • ■ ■ ^ ' ■ 

-n..*'e* 3 Hdrrisoh tvptt .-o f .k^ tb^ h;i* iwmc logged b| W"l? stc - ,n ' thmujt.b ?hc clement. Care muse be 

bv ^veed ..oJ oth« debut ' ^ "J 1 " ( CXC 1 Ced thC i ^« , ' ^thtck^:- 

n>e*ic when the clement is badly clewed with scawtc 1 . 

the cfoncnrs show mJteatKm* .'of grew or 
.d^aWe w c)^ rbem^ cpteifia) page 
;ipprecuhte- >.leposus of scale are 0Me*iV sec 


c. possible trouble: 


Leakage in the fresh water cooler may be either in 
the element or from the casing. Leakage from the 
casing may be observed readily during the frequent 
inspections for leaks that should be made of the cool- 
ing system. If a cooler gasket is damaged, the heat 
exchanger should be removed from the piping so that 
the flange faces may be tightened evenly after installa- 
tion of a new gasket. 

Leaky elements are more difficult to detect. How- 
ever, an appreciable decline or rise in the fresh water 
tank level (at the same temperature) usually indicates 
leakage. Hydrostatic testing of the cooler elements is 
the surest method of discovering leaks.' 

To test the cooler element for leakage: 

(a) The element must be removed from the 


(b) The discharge side of element is blocked off. 

(c) A pressure gage is attached to the inlet line 

of the element. 

(d) Low pressure air is admitted to the inlet side 

of the element, and the element is im- 
mersed in a tank of water. The pressure 
shown on the heat exchanger name plate 
must not be exceeded. 

(e) Careful observation is made to detect any 

bubbles issuing from the element, for 

this indicates leakage. 
The above test may also be performed without im- 
mersing the element, by filling it with water under 

1. Causes and prevention. Leaky cooler elements are 
due mainly to: 

(a) Corrosion of the element. 

(b) Erosion of the element. 

(c) Operation at excessive pressure. 

(a) Corrosion of the element. Corrosion may be either 
localized or general in extent. Usually, when a hole 
has been formed by corrosion, there is a strong prob- 
ability that corrosion has occurred throughout the 
element. Inspection should be made to determine if 
this is the case. 

Corrosion may be effectively reduced by the follow- 
ing practices: 

(1) Regular treatment of all fresh water used in the 
cooling jackets in accordance with Chapter 41, Sec- 
tion II, Part 10 of the Bureau of Ships Manual. 

(2) Inspection of the zinc plugs and plates when the 
cooler is first put into service. Later, on the basis of 

Digitized:, GOuQle 

these inspections, it will be possible to predict the life 
of zincs in a particular installation. Hints on how to 
inspect, and when to replace zincs are given on 
pages 127-128. 

(3) All coolers should be vented to remove en- 
trapped air. This hinders corrosion, and also fills the 
coolers with water, insuring against reduced effi- 
ciency caused by air binding. Inspection should be 
made to insure that the water is not being aereated by 
air leaking into the system through the pump seals. 

(b) Erosion of the element. Eroded holes are caused, in 
most cases, by the impingement on the element of grit 
particles at high velocity. This grit may be intro- 
duced through a defective sea-water strainer when the 
ship is in shallow water. The strainers must be kept 
in good condition. 

Increasing the water flow above rated capacitv 
should be avoided, as the water at high velocity can 
alone cause erosion by cavitation. In installations 
where several pumps take suction from the same sea 
chest, excessive velocities through the heat exchanger 
may exist when only a few of the pumps are being 
operated. This is due to the property of a centrifugal 
pump which causes a greater discharge when the head 
(suction head in this case) on the pump is reduced. 
Head, on salt-water pumps, should be regulated bv 
partially closing the discharge valve when other sea- 
water pumps taking suction from the chest are not 

The cooler should be cleaned when it is found that 
proper fresh-water temperatures cannot be maintained 
without greatly increasing the flow of sea water. 

(c) Operation at excessive pressures. The maximum 
operating pressure is stamped on heat exchanger name 
plates. Care must be exercised never to exceed this 

When exchanger elements become clogged with 
scale or other material, more water must be circulated 
to obtain the same cooling effect. More pressure is 
necessary to force a given quantity of water through 
the exchanger when it is clogged. 

Heat exchanger elements must be kept clean. 

2. Repair. See 2. Repair, page 127. 

7B3. Shell-and-tube type. This type of heat ex- 
changer is shown in Figure 7-1. It is usually cmploved 
where large capacity is required. 

In principle it is exactly like the Harrison type and, 
consequently, the troubles encountered in both are 
quite similar. However, some cleaning practices are 
not applicable to both types. 

1 Origiral from 



A. possible trouble: 


Sec a. Possible trouble: Excessive scale on cooler element \ 
pages 138-139. 

1. Causes and prevention. See Causes and prevention , 
pages 138-139. 

2. Repair. Shell-and-tube type heat exchangers are 
never to be cleaned by use of acid. An air or water lance 
is to be used in removing scale deposits. The use of 
steel bristle brushes is not advised, as they will scratch 
most tubes and thereby accelerate corrosion. 

b. possible trouble: 
clogged cooler element 

See b. Possible trouble: Closed cooler element, page 

1. Causes and prevention. See Causes and prevention, 
page 139. 

2. Repair. The deposits should be removed with a 
water or air lance. Oil films may be removed by flush- 
ing thoroughly with steam. Circulation of carbon 
tetrachloride, or a similar solvent, is not generally 
advisable due to the great quantities necessary for 
large coolers. 

c. possible trouble: 


See c. Possible trouble: Leaky cooler, page 140. 

1. Causes and prevention: See Causes and prevention, 
page 140. 

2. Repair. A leaky tube must be replaced at the 
earliest opportunity. In most instances, it will be pos- 
sible to block off the faulty tube by inserting a wooden 
plug in each end, until it is possible to replace it. 


7C1. General. The following are the principal 
types of pump used in Navy diesel cooling systems: 

1. Centrifugal 

2. Gear 

The circulation of salt or fresh water or both in the 
engine cooling system is accomplished by pumps. 
Some engines are also equipped with pumps which aid 
in removing water from the bilges. 

The rate of flow of the coolant is controlled by vari- 
ation of pump speed, or by manual or automatic 
adjustment of valves. The quantity of flow required 
varies with engine speed, load, etc. 

Digitized by GQoQIC 

In general, three classes of cooling system pumps are 
in use in the Navy : centrifugal, gear, and plunger. As 
the latter type is not so widely used in conjunction 
with diesels, it will not be discussed separately. 

On some engines, the cooling pumps may be directly 
driven through gears or belts. On other installations, 
they are sometimes detached and driven separately by 
electric motors. In many installations, both attached 
and detached pumps are used. Detached pumps in that 
case are used for standby service; also for priming and 
after cooling, when engines are shut down. 

Pumps must be maintained in good condition to 
avoid a reduction in their capacity. Insufficient capac- 
ity might endanger the engine in an emergency, when 
full speed and power are required. Particular atten- 
tion should be given to maintenance of pump clear- 
ances as specified in the instruction manual, and to 
proper packing of pumps. 

7C2. Centrifugal pumps. Centrifugal pumps are of 
many varied types. They may be separately driven or 
attached to the engine, single or double suction, open 
or closed impeller, reversible or nonreversible, etc. In 
all centrifugal pumps, however, water is sucked into 
the center of the impeller and thrown at high velocity 
into the casing surrounding the impeller, where the 
velocity is largely changed to pressure. 

In all such pumps, sealing devices, usually of the 
stuffing box type, are provided to prevent leakage of 
water, oil, grease, or air around the impeller shaft, or 
around the impeller shaft sleeve when this sleeve is 
used to protect the shaft. 

Generally, the clearances between the impeller and 
case must be small in order to reduce the internal leak- 
age. Wear rings are frequently employed between the 
impeller and case, so that the desired small clearances, 
when lost, may be regained readily by replacing these 
rings. The rings are designed to take most of the wear 
(see Figure 7-9). Figure 7-3 illustrates one type of 
centrifugal water pump employed in diesel engine 
service in the Navy. 

It should be remembered that all centrifugal pumps 
are extremely sensitive to restrictions in their suction 
piping. The suction screens and piping must be kept 
clean. The suction lift should be as small as possible, 
or the suction should be under a positive bead when 
practicable. The suction lines should be kept short 
and with as few bends as possible. This is particularly 
important where hot fluids are being pumped, as they 
tend to vaporize under high suction lifts, increasing 
the probability of cavitation and loss of suction 
through vapor lock. 

Original from 


ipIIii iiii in"- 

wa<^ 23 g, * 

i 1 $ 

Worn ■ 

' a £ aum rhc * haft casing by pulling ihwn on rhc 
roo nghel-.y st will tend to bind again:** the sh.Ut. cause 

head on rbc p»mp will be increased and |<*s waterwitt tightened ani* tb'Vhe pomr/Mere 4 .small amount «>f 

leakage is scij] prcsetVc , In no case should the adjusting 

be pumjxrd. These pas&agts Must be kept clean. , leakage \i> mil prcsetrc. m no 

(0 mwz. dfwtio* <;} futxnm 'Some ccntrifogal "^^^ 

just snug. In masc cases. 


per Hunute is 

•v*^: . If v.. - • • 

such case, the impeller bhdes «e general I v curved. r $omc fW*** 

Figure 7-S illustrates the pro^r direction of rotation *» ,W S device* that require no adjust 

for such a?s impeller Ob many pumps an arrow is 1,0 1 nccc * co * ea * to prevent scoring of the shaft. The 
prbvidtsd on che pmtip case to indicate the correct 
direction of rotation. 

2. R^<f ; Tk source of troufefc 


chc writer being 


Jiti«m w ill minimize rfuis condition. > allowed w run dry. or ft sqartsd Wjthoat sufficient 
> of kcjrjti^ Excessively worn bear- pnttafc ami operates dry, rnctson between chc impeller 

screens in £uucl eon J 

(» |&J cmttWhri of 

tf)gs irjiiy allow the pump shaft to drop enough to or case and the wear rings wiJ) he great iv njcrtuxed' 

M« TDAIKIlia/- HAfcHlAl I. | MAVY 

Ways should be inspected to make c«- W W mt. Bought)^ of the , hair wd! «tf <*f 
tain that the keys fit properly. A loose kev will allow the. scab rap,dt.y, bcore* or puled sh^tt, . roust be 
the impeller to work back and forth on the shaft, and repJaced. 


Figure 7-9. Location of war rings on difforont typos of centrifugal pumps. 

h. possible trouble: 


The discovery of this trouble may be preceded by 
rapid wear of the packing or other shaft seals. Re- 
placement of the packing will be found ineffective in 
stopping leaks. This is due to the shaft dropping and 
resting on the packing as a bearing. 

Excessive end play of the rotor shaft may also be 
caused by poor condition of the bearings. 

Bearings should be inspected carefully for signs of 
pitting or scoring: This is especially important in the 
case of frictionless bearings. Overheating of friction- 
less bearings may be caused by overlubrication (see 
Chapter 16). 

1. Causes and prevention. The principal causes of 
frictionless bearing failure are discussed in Chapter 16, 
and those for journal bearing failure in Chapter 15. 
However, one cause most prevalent in sea water 
pumps is entry of sea water into bearings. Sea water 
quickly ruins bearings by corrosion. Sea water gener- 
ally enters bearings by leaking past shaft seals. 

In some sea water pumps, water leaking from the 
stuffing box leaks into the "cradle" below the stuffing 
box. Unless the cradle drain hole is unobstructed, 
water may fill up this cradle and leak into the bearing 
housing. This drain hole must be inspected frequently 
and kept clean and unobstructed. 

The bearing housings should be inspected for signs 
of salt water entry when the pump is being repacked. 

2. Repair. The bearing must be replaced in accordance 
with the instruction manual. Oil and water seals 
must be in proper condition before placing the pump in 
service. The bearings must not be overlubricated. 

i. possible trouble: 


A reduction in pump capacity, inability to develop 
rated pressure, or complete failure of the pump to 
deliver water may be caused by excessive wear of the 
wear rings. Not all centrifugal pumps arc equipped 
with these rings. 

1. Causes and prevention. Wear of the wear rings is 
expected. They are designed to wear instead of the case 
or rotor. However, the life of wearing rings is greatly 
reduced by: 

(a) Allowing the pump to run dry. 

(b) Pumping fluid containing abrasive material. 

(a) Allowing the pump to run dry. See page 145- 

(b) Pumping fluid containing abrasive material. See 
page 146. 

2. Repair. Replace worn rings. 

7C3. Gear pumps. These pumps are of the posi- 
tive displacement type. They are identical in principle 
of operation with the gear type lubricating oil pumps. 
They may be attached to the engine, or driven by a 
separate motor. The pumping gears are constructed of 
metal or moulded neoprene. Two common types arc 
illustrated in Figure 7-10. 

In some pumps, the gears do not contact one another. 
This greatly reduces pumping gear wear. This prin- 
ciple is similar to that employed in the gear type 
Roots blower, discussed in Chapter 2. In such cases, 
it is imperative that the driving gears be timed so that 
contact between the pumping gears does not occur. 

The sealing devices employed to prevent the leakage 
of oil, grease, or water are so similar to those used in 
centrifugal pumps that reference may be made to the 
material dealing with seals on centrifugal pumps. 

a. possible trouble: 
insufficient discharge 

This trouble is recognized by a rise in the water and 
lube oil temperatures. If no water is being circulated, 
this should be noted immediately after starting the 
pump. A careful inspection should be made immedi- 
ately after starting the pump to see that the water is 
being circulated. Extreme damage to the pump, cyl- 
inder block, liners, heads, and other costly engine 
parts can occur if this precaution is not practiced 

1. Causes and prevention. The usual causes of insuffi- 
cient discharge are: 

Digitized by GOOQle ™ fr ° m 


^-.i S:< -■ ■ v. v .. ... 

This troul 




• , - ME1AL GEAR tyPE 

^••T 'J* •«•.. Ff • ; * 

* J "' ' • >, 
~'7« k . - ; ' > i i v < # »V . . >* . • rV 

S£§^i ^&Vr* J 


_— n<n to ^emMe the panics in a ditty condition.. Such 

* «« donate consulcrahlc war of the bcrim* 

— iHs ml Ms mstf — ,h,u:, uiij r ,a I( ,, 




ft$ur* 7- /5, N*opr*n* pmr damaged Ssy hwtti«# 



7D1. GsnsraK Valves many types are used io 


water p^siqg throiigh coolers- mufflers, and strainers:. strict! v to avoid error. Pr 
Such valv^^^vc^pije-hTilet, of fixed s&e. snd twaout- . 
lets, who$c:/rif/:<tive sises can he varied simultaneously 
either By manual or by rnraBbstatic adjustment, 
Thus* by increasing the sis.e of one our let and reducing 

ifae sue at' the other pvxicX at the same time, vtetcx 
mav be diverted from one outlet to the other 

Pigarc 6-3 on page 122 iHustrares two rypicul closed 
cooling systems in use in the Navy, h will noted 
that only ' thermostatic /falves 'aire employed in the 
portion of the systems shown. However, manually 
operated proportion nig v^Jvies may be used to regulate 
the: flow of coolant to wer. type exhaust mufflers and 
other auxiliaries. Also, older engine installations are 
sometimes ' equipped with manually operated valves 
for controlling engine Coolant r em pera torts. 

It is imperative that til valve*, he kepc in proper 
condition to avoid the:, crti harr asstttent of 'being unable 
to regulate cooling water fcmt>craturc readllv in an 

vvarer temperature readily in an 

II 1111 1 

7D2. Manually operated valvar. general. Manu 
ally operated valves are primarily of either the gate, 
globe, or plug cock type' Gate and globe valves have 
been discussed previously tin Chapter 6. The lubri- 
cated plus, cype. is discussed here, 

7D3. Manually op«r«ketj vaW lubricated 
type. Valves of this type employ a routing plug 
drilled for the passage of the thud Rotaffon 
plug changes the posit ion of" ch,- dr.; lied passages witl 

cation insures nghtness, maximum hit, and ease '$hc following precautions should be observed in 
of operation. lubricating plug valves. Lubricate the valve by rcmov- 
Figure 7-16 illustrates one commonly used type of iag the lubricant serscrcw and inserting a stick oi 
lubticaied plug valve, iubneant. Th 
: L . — — _ upon the flat 

□g cocks are 



or ir 

lubrication mav cause the valve to 
or tnav cause 

factum's lubneuved plug cocks are 

•A a 

Atactic** Car a?i*i KMHidrV 

' Aftet msert.on, thciuhncnt >s forced into the valve 

the lunncani setscrew mud the lubricant 

proper tubricatiotiOl [*4ug valves is ignorance of proper lubricated under pressure 


: — vJic^non of improper 

7D4. Themostotic valve* ; gen^oL Most .thermo- 1. Qmstjtn4 pwrnttau. The oajy caasc i<»r lift proper' 

merely of 
$cs the 
increase in 

spring tension will require $ higher ^;rn perjure to be 
7D5, Th^rmo^atic vdves; automatic temperotow rcacbed hetorc the valve will act to divert 4 greater 

TJv^'i •' thennosf.ufk buih removed from die ship's piping arid 

nuke w£ 1 he. Mb is. at a teroperatvrs beh^v li)0° F.) 

;(a)Xtemjn«ui Crunk pin (4C0 is reared until the 
mdiciupr pointer (9) is m the th» HMon ath: position* 



%«r» 7-17. Futtwfyphon automatic t*mp*ni«t*+* 9 vf«ti>?, The ad wheel (37) is. turned until the pm. 

(7) m'suchc* «tiih number 2 on the sede pJ;ue (6); 

A remote bulfe, connected to the upper end of the iocfchnr .('43)' j$ -loosened and- the valve- stem (44) 



l^BfV^ ' ^ .--v ^f^s^iv^uf («6)F«Noe«-ri6Mr out y, so 


Ml 1 


located in cither aurJer-irom or inter-to 


• 1 1 ■ If : 

the evgitit; position, the nut mas?: be av rhc top. Sec Figure 7-19 

flbid at thematic bulb between the Value . ^ ^ ^ghv th^rf ^1 

ojinecf for CO above amLa temperature appro* mia td )< H^fr^^Tr ^ ^ 

•;Uc.itcd fry coojmg water 
- vahic specified in the 
imtinbertd however, 
cmfxrrature does nor 

I (uVniethertiitfsitfi must be removed frofjj fh.c e.ugme. 

"OftEMOveiB'tiLS f-HOM - i 

■ • 1 


|s « start u> open, i m* t^pera^irc is genera.) jy specmca 

* in the HiAii'ueiion.nWa^i ii is in the rceigltbofhood 

i of 1 55? f tor mabv'enguicrs. "The' instruction manual. 

: " - — 

S3 « ft^l 




resulting irom flexure ai t 
nfe&ttts muK be carefully w 


A. possible trouble: 


This trouble is difficult to recognize by any means 
other than visual inspection; and even this is quite 
difficult in many engines. Unfortunately, the effects 
of this trouble may manifest themselves in the form of 
cracked blocks, liners, cylinder heads, exhaust mani- 
folds, scored pistons and liners, or other serious 
derangements. Cracks are caused by uneven cooling of 
the parts due to blankets of scale. It is advisable to 
take every possible step to minimize scale formation, 
and to make inspections of cooling passage surfaces at 
every opportunity. When no other means of inspec- 
tion is available, a fair check of the jacket condition 
can be made by inspection of the inside of the jacket in 
the vicinity of inlet and outlet connections. 

1. Causes and prevention. Complete prevention of 
scale formation is impossible when sea water is circu- 
lated through the cooling passages. It can be mini- 
mized, however, by the maintenance of proper cooling 
water temperatures. Sea-water temperatures should 
never exceed 130° F. 

Control of scale formation is much easier in closed 
cooling systems because it is possible to treat the 
coolant chemically. 

The principal causes of rapid scale formation in open 
and closed cooling systems, respectively, are: 

(a) Operation with elevated sea-water tem- 


(b) Use of hard fresh water in closed cooling 


(a) Operation with elevated sea-water temperatures. 
Where the open system of cooling is employed, it is 
imperative that the discharge temperature of the sea 
water be limited to 130° F. If possible, a 125° F dis- 
charge temperature is preferable (see a. Possible trouble: 
Excessive scale on cooler element, pages 138-139). 

(b) Use of hard fresh water in closed cooling systems. See 
a. Possible trouble: Excessive scale on cooler element, 
pages 138-139. 

2. Repair. Scale removal from cooling passages is 
effected by chemical treatment, because mechanical 
cleaning is impractical. Scale should be removed by 
treatment with hydrochloric acid, pyridine (an inhibi- 
tor to reduce attack on metal by the acid), and fresh 
water. In closed systems it is generally possible to 
circulate this cleaning solution, but in open systems it 
may be necessary to block off all connections, fill the 
system with cleaner, and allow it to set. 

Full instructions for the cleaning of cooling water 

Digitizes by G<X 'QIC 

passages will be found in the Bureau of Ships Manual, 
Chapter 41, Section II, Part 10. 

b. possible trouble: 
corrosion of cooling water passages 

If the corrosion is sufficiently severe, it may be 
discovered by the observation of leaks through the 
passage walls. Pitting of the water passage walls, or 
accumulation of rust in passages, indicates corrosion. 
However, as corrosion is difficult to recognize until 
damage has been done, it is highly desirable to take 
every possible preventive measure. 

1. Causes and prevention. Corrosion may be of several 
different types. Some of the causes of corrosion arc: 

(a) Improper of cooling water. 

(b) Failure to use rust inhibitor. 

(a) Improper ' 'pH' ' of cooling water. The symbol is 
an index of the comparative acidity or alkalinity of 
cooling water. The proper range of to prevent 
corrosion may be determined by use of the corrosion 
control indicator described in the Bureau of Ships 
Manual , Chapter 41. If the test indicates improper 
^H, it is necessary to treat the cooling water as 
specified in Chapter # 41, Part 10. 

(b) Failure to use rust inhibitor. Rust in the cooling 
system indicates corrosion by oxidation. This type of 
corrosion cannot be entirely prevented by treatment 
with trisodium phosphate. 

For better control of the rust, soluble-oil type in- 
hibitors have been developed which, when added to 
the cooling system in a quantity equal to 1 percent of 
the total capacity, will coat the cooling surface with 
an extremely thin protective film. It should be remem- 
bered that this treatment will not be fully effective 
unless the cooling passages have been thoroughly 
cleaned prior to treatment. 

c. possible trouble: 


If the leaks are external, they are readily detected 
when routine inspections of the cooling water systems 
are made. However, if the leaks are so located that 
they are not externally visible, they may not be de- 
tected until the lubricating oil is discovered to be 
contaminated with water, or evidence of water is 
noted in the engine cylinders. 

Water in lube oil may frequently be detected by 
noting an emulsion or cloudiness of the oil on the dip 
stick, or by centrifuging a small sample of the lube oil. 
It should be remembered, however, that small amounts 
of water in the lube oil are inevitable because of the 



condensation of steam (present in the gases of com- 
bustion) in the crankcase. Any indication of unusually 
large quantities of water should be cause to suspect 
that water is leaking into the system. 

Water in the cylinders may be detected when the 
engine is barred over with the indicator cocks open, 
prior to starting after a shutdown. The engine must 
not be started when any appreciable amount of water 
is discovered in cylinders until the source of the water 
has been definitely established and the trouble reme- 
died. The presence of an appreciable quantity of water 
in the combustion chamber during the compression 
stroke is as dangerous as a corresponding amount of 

1. Causes and prevention. Leaky cooling passages arc 
due to: 

(a) Cracked walls. 

(b) Corroded walls. 

(c) Poor condition of gaskets. 

(a) Cracked walls. Cracking of cooling passage walls 
may be the result of uneven cooling of the metal, or of 
subjection to high stresses from mechanical shock. 

The cooling water must be maintained at the tem- 
peratures specified in the instruction manual, and the 
cooling passage walls must be kept scale free. Cold 
water must never be added to a hot engine, for this 
may result in uneven cooling and possibility of frac- 
ture from thermal stresses. 

Cast iron cooling passages are sensitive to shock. 
Detonation of explosives, striking with hammers, etc., 
can cause cracks to develop. The engine must be 
properly mounted to prevent harmful vibration that 
may cause cracks. Insecure mounting, due to loose- 
ness of mounting bolts, must not be permitted. 

(b) Corroded walls. Corrosion may so weaken the 
cooling passage walls that holes are developed by 
erosion. In closed cooling systems, treatment of the 
fresh water to inhibit corrosion will reduce such 
casualties. In sea-water systems, proper attention to 
the maintenance of zinc plugs and plates is necessary to 
inhibit corrosion (see c. Possible trouble: Corroded zinc 
plugs and plates, pages 127-128). 

(c) Poor condition of gaskets. The majority of the 
cooling system leaks are caused by the poor condition 
of gaskets. Much difficulty can be avoided by proper 
attention to gasket maintenance. A poor gasket must 
never be installed, as it can lead to serious trouble later. 
A small leak, initiated by a poor gasket, can cause 
corrosion and erosion of costly metal parts in the 
vicinity of the leak. 

When facilities and experienced personnel are avail- 
able, many cracks can be repaired by welding. 

2. Repair. Small cracks in cooling passage walls 
can .be repaired satisfactorily by a drilling, tapping, 
and peening process when the cracked member is one 
that is not normally subjected to much stress. Such 
processes are used instead of welding when welding is 
impossible or very difficult. The processes, one of 
which is referred to as Metalock, are not approved for 
such repairs on all types of equipment. Generally, 
these should be used only where stresses are not too 
high, and where possible failure of the part will not 
be a serious threat to the operation of the vessel in an 
emergency. For further information on Metalock and 
related processes, see Chapter 10. 

Leaks from gaskets are easily repaired by replace- 
ment of the faulty gasket. The surfaces between which 
the gasket is to be placed must be clean and free from 
projections that will interfere with proper sealing. 

7E3. Piping. Cooling system piping, as used in 
conjunction with diesel engines in naval service, is of 
several different types. It is therefore advisable for the 
engineering force to be familiar with the proper 
installation and maintenance procedure for all types 
of piping. 

Sea-water piping is almost universally seamless 
copper-nickel brass or copper tubing. Connections 
between lengths of tubing are made either by silver 
soldering or brazing, or use of flared fittings. Soft 
solder has been used in the past, but it is being sup- 
planted by silver alloy brazing. No type of fitting 
which crimps or nicks the tubing is permitted. For 
this reason, ferrule type fittings should be replaced 
with the flared type at the earliest opportunity. 

Fresh-water piping is usually galvanized steel tub- 
ing. Small lines, or those in which sharp bends are 
unavoidable, are frequently of copper tubing. Flared 
joints are used with this tubing. 

Larger sizes of copper and brass tubing, or pipe (pipe 
is thicker than tubing by an amount known as the 
threading allowance) are fitted with flanges to permit 
rapid coupling. Some form of gasket is provided 
between flanges to aid in sealing. 

Flexible metal tubing is often used between the 
engine and piping which is rigidly secured to the hull. 
This has the effect of greatly reducing the transmission 
of vibration to the piping, thereby lengthening its 
useful life. 

Lines must be kept clear, as any restriction to the 
flow of cooling water may result in a part becoming 
overheated and failing. 

Leakage of lines is a source of great annoyance, and 
gives an impression of general laxness on the part of 

Digitized by GOOOle *™ 



the engineering force. Making connections with care 
will eliminate much of this trouble. 

a. possible trouble: 
clogged water line 

This trouble may become evident when it is noted 
that no water, or not enough water, is being circulated 
to any part of the engine. Inspection of the lines by 
disconnecting them and attempting to blow through 
them will aid in discovery of such a condition. 

Clogging should not be permitted, as it imposes an 
extra load on the water pumps, and it may be instru- 
mental in causing loss of suction. In most cases, how- 
ever, clogging will affect the coolers more quickly 
than the piping, because of the much smaller passages 
in the coolers. 

1. Causes and prevention. The conditions that usually 
lead to clogging of water lines are: 

(a) Poor condition of strainers. 

(b) Excessive scale formation. 

(a) Poor condition of strainers. If the strainers are not 
operating properly, they may allow seaweed and other 
debris to clog the salt water lines. The most serious 
effect, however, of poor condition of the strainers, is 
the quick clogging of the numerous small passages in 
the coolers. The strainers must be kept in good 

(b) Excessive scale formation. Scale inside the piping 
is of two general types : hard water scale and rust scale. 
Rust is readily identified by its reddish-brown appear- 
ance; hard water scale, generally called simply scale, 
usually ranges from white to gray in color. If rust is 
detected in the fresh-water piping, treatment of the 
fresh water with soluble-oil type rust inhibitor is 
indicated. The formation of scale may be greatly 
reduced by treatment of the fresh water with tri- 
sodium phosphate (see a. Possible trouble: Excessive 
scale on cooler element, pages 138-139) and by main- 
tenance of the sea-water temperatures below the 
recommended maximum. 

2. Repair. Lines clogged with seaweed or debris 
may be freed by running a stiff wire through them. 
Scaly rust may be blown out with a steam or air hose. 
Hard water scale must usually be removed by circu- 
lating cleaning solution through the engine cooling 
system. See Bureau of Ships Manual, Chapter 41, 
articles 506 to 511. 

After it has been cleaned, the piping should be 
inspected for signs of excessive corrosion or erosion. 
Deep pitting, which may cause leaks to develop later, 
usually necessitates replacement of the piping. 

Digitized by GOuQIC 

B. POSSIBLE trouble: 


This trouble is readily discovered when the cooling 
system is inspected. 

Careful inspections of the cooling system must be 
made once each watch, or at such intervals as the 
engineering officer considers necessary. However, 
operating personnel must be continually alert for 
incipient leaks and other troubles before they have 
become so serious as to require considerable time for 

Much of the difficulty with leakage around connec- 
tions, and in the piping proper, can be prevented by 
proper anchorage of the piping. Much vibration can 
be eliminated by simple alterations of pipe supports; 
in some cases, an extra point of support will be a 
great help. 

Men should be cautioned against using piping for 
hand or foot holds, for securing chain falls, or for 
supporting weights. 

1. Causes and prevention. Leaky water piping is, as 
a rule, a result of: 

(a) Poor piping connection. 

(b) Hole in the piping. 

(c) Vibration of the piping. 

(a) Poor piping connection. Connection of piping is 
accomplished by the following general means: 

(1) Welding. 

(2) Brazing. 

(3) Silver soldering. 

(4) Flanged connection. 

(5) Flared connection. 

(6) Threaded connection. 

(7) Combinations of the preceding. 

From this list it is evident that members of the 
engineering force must have considerable knowledge 
to cope with difficulties arising with these various 
types of connections. Familiarity should be acquired 
with each type. To avoid trouble, the precautions 
given below should be observed in making connections. 

(1) Welding. This method is used upon steel tubing. 
Special weld fittings are used. The surfaces to be 
welded must be very clean. All slag, rust, and scale 
must be removed prior to welding. A wire brush, 
emery cloth, or file should be used to clean the surfaces. 
Loose weld beads must be removed from the interior 
of the piping. 

(2) Brazing. Most copper, brass, and copper-nickel 
tubing is silver brazed. Such joints arc far more 
resistant to vibration and elevated temperatures than 
soft soldered joints. 

1 Qrigiral from 


foJlowinc precautions should be observed in All mccha&fcs who are required to d«* .considerable 

; ■ 

the Ijcuijg. the fitting a_ 
pipe 'masc be 'h^t eoc\ug'h to allow the solder to Haw 
freelv. A torch, ;«jot a soldering iron, should be used. 
' enough flux should he used to barely caver the 


•.;^~-.';.>v«v :-;: i '.'V; 


GomKit.uji \ e^cls or othei vessels where rhc liaics arc water. 'The den tibg Of bcfidtog of copper J i«k* so rhat 

subjected ro shock Of vibf;it«*ci of Any considerable. rhcy'.*re redact h? cms^ectsonjJ area muse be 

tnagoiciufe Tb«s }>tc.war of the numerous hulurev avoided (see figure 7-24). When making bend* of 

of piping at the first -exposed -thread. An -w^mpk of copper lines, onlv the proper cools should be uscft. 

this cvpeoffaiiurc h sho^nm Figure 7 :y. (^V^wn^** 

. IW«.W» ■ ™ • Shock or continued V&mJon wffl "cause the failure 

1 ioini of c5oe it is of ^rwdcd pipe. IfsuyilvV errfefcs form at the roar of 
h*r ™r,;i thu-,J s Accxpos.dthrc.d^sccF^urc .7-23), 

W hen it is necessary ro thread a 

after an ring . rbc pipe. The dk should be started 
sir^tht^ oil Ubcr.div ut>ed the diciru^st. ^ 

When imporuat lioes subjected to shock .or vibra, I i 

controlled, in maay 
| anchorage roethods. 

many tUngcd f 

or so 

perfecUy Ciean , These surfaces mast nor be nicked this cm be deme by heating the tubing . «y uh. a torch, 
>a-:ttciied. then iteming ir in cold water Tu avoid local over- 


• ■ ; 

Clogged s*o-water strainer, 


occur. A dangerous degree of clogging may result 
from failure to clean the strainer at frequent intervals. 
Only by careful inspection of the strainer baskets at 
frequent intervals can the need for cleaning be recog- 
nized. In some installations, inspection is facilitated 
by a plastic or glass strainer housing. In other cases, 
it is a very simple matter to unscrew the hold-down 
clamps and remove the basket for inspection and for 
cleaning, if necessary. 

2. Repair. Cleaning of seawater strainers is accom- 
plished by dumping debris from the basket and blow- 
ing out the mesh with compressed air. The housing 
should also be cleaned, if necessary, to facilitate 
replacement of the strainer basket. It should never be 
necessary to force the basket into place, as this may 
Cause it to be damaged. 

Collection of debris outside the basket will occur if 
the strainer is not installed with the arrow on the 
housing pointing in the direction of sea-water flow. 

b. possible trouble: 
corroded strainer basket 

This condition must be detected by inspection in 
order to avoid clogging of the sea-water passages in 
the coolers and elsewhere. Figure 7-27 illustrates 
portions of a yellow brass strainer that has been sub- 
jected to deztneification, a form of galvanic action. 

1. Causes and prevention. Corrosion is inevitable with 
most types of strainers. The life of strainer baskets 
varies from three months to a year or more, depending 
on sea-water temperature and other conditions. Where 
corrosion is very severe, the cause may be failure to 
use a proper strainer basket. In severe cases of corro- 
sion, yellow brass strainer baskets should be replaced 
with baskets of monel metal, copper nickel, or similar 
corrosion resistant metal. 

2. Repair. Corroded strainer baskets cannot be 
repaired successfully. A liberal replacement stock 
must be maintained. 

Digitized by GOOSES 

Origiral from 



8A1. General. It is the desire of every engine 
operator to have an engine that starts easily. Starting 
has been one of the major problems of the diesel en- 
gine. The majority of engines now in use by the Navy 
employ either a compressed air starting system or an 
electrical starting system. Other systems employed to 
start diesels are the cartridge starters and auxiliary 
gasoline engine starters. Inasmuch as the two latter 
systems are seldom used on naval vessels, they will 
not be discussed here. 

To have an engine that starts easily, it is important 
that all the engine systems be in proper working order. 
It is not enough merely to turn the engine over at the 
required starting speed. It is also necessary to have 
the fuel transfer pump, fuel injection pump, injectors, 
and the cylinder assembly all in good condition and 
properly adjusted. If these parts are not in good condi- 
tion or are improperly adjusted, the starting system 
will have to turn the engine over for longer periods of 
time to effect starting, thus greatly increasing the wear 
on and maintenance of the system. 


8B1 . General. Electrical starting systems are be- 
coming more widely used. Although in previous years 
electrical starting systems were limited to smaller 
engines, such as the automotive or boat type, they arc 
now being used on some of the largest engines. 

The electrical system offers some advantages over 
the air starting systems. The most important advan- 
tage is that the starting air valves and all the asso- 
ciated parts are eliminated. 

Troubles encountered in the electrical starting sys- 
tems are relatively few. Most troubles develop from 
improper use, care, or maintenance. 

Batteries are not covered in this chapter, but are 
thoroughly covered in Chapter 9. 

Digitized by GO * 1 

A. POSSIBLE trouble: 

The electric starter motor, in order to have proper 
commutation, must be kept clean and remain dry at 
all times. 

1. Causes and prevention. Dirty and fouled starter 
motors arc caused by one or more of the following 
careless practices: 

(a) Removal of dust cover. 

(b) Water leakage. 

(c) Excess lubrication. 

(a) Removal of dust cover. Most starter motors are 
equipped with a dust cover to protect the commutator 
and windings. Frequently the cover will be removed 
and the operator will neglect to replace it. Often the 
cover is removed as an aid to ventilation and cooling, 
but this should not be done. The starter is used only 
for short periods of time and should not heat up exces- 
sively. The starter should never be operated for periods 
longer than 30 seconds. If the engine does not start in 
that length of time, something is wrong with it. The 
various systems should be checked in this case. Par- 
ticular attention should be given the fuel system, as it 
is in this system that the majority of starting troubles 

(b) Water leakage. Electric starter motors are usually 
mounted low on the engine at crankshaft level; conse- 
quently, there is usually a water pump, oil pump, 
piping, or jacketed manifold mounted above it that 
provides a potential leak that will drip onto, or drain 
into, the motor. 

Such moisture, whether it be fresh water, sea water, 
or oil will not only cause the commutator to become 
fouled, but will also cause deterioration of the arma- 
ture and field windings and the shaft bearings. 

Every precaution must be taken to prevent moisture 
from reaching the starter. If the starter appears to be 
in a vulnerable spot, it is recommended that a sheet 

Original from 


metal shield be constructed above it to catch and carry 
away any oil or water that might drip onto it. 

(c) Excess lubrication. If the operator is careless 
about lubrication, he may put too much oil or grease 
in the shaft bearings. When this is done, the excess 
lubricant is liable to leak past the seal and onto the 
commutator and brushes. Inasmuch as oils and greases 
are poor conductors (although good insulators) the 
brushes will make poor contact with the commutators, 
causing sparking and heating of the commutator, and 
burning of the brushes. In the extreme case, the 
oil will oxidize and form a gum-like deposit on the 
commutator, causing further restriction to current flow. 

2. Repair. Methods used for cleaning commutators 
are dependent upon the severity of the case and the 
type of deposit. Grease and oil can safely be removed 
by using carbon tetrachloride. Carbon tetrachloride is 
recommended because it is noninflammable. Gasoline, 
kerosene, and alcohol should not be used as they are 
inflammable and the latter will, in addition, remove 
shellac should shellac be the protective coating for 
the windings. 

The commutator can be cleaned further by using fine 
sandpaper of a grade of 4/0 or finer. Carborundum or 
emery paper should not be used. 

If the commutator is scored, or is pitted, it will be 
necessary to turn it down on a lathe. After turning the 
commutator down, the insulating material between 
the segments must be undercut. 

b. possible trouble: 
burned brushes 

While brushes are subject to normal wear, with 
proper care they can be made to give extended service. 
Due to the high currents which flow when the starter 
is operating, the condition of the brush is of prime 
importance. If the brush is improperly cared for it 
will quickly burn out. 

1. Causes and prevention. Burned brushes are caused 

(a) Loose holders. 

(b) Improper seating. 

(c) Overload. 

(d) Dirty commutator. 

(e) Loose connections. 

(a) Loose holders. It is most important that the 
brushes be firmly supported in the correct position. If 
they are not supported properly, the area of contact 
will not be constant and thus the current per unit area 
at the point of contact will vary, resulting in an over- 
load when the area is small. 

Digitized:, CjOuQIC 

(b) Improperly seated. New brushes that are being % 
installed should first be secured in place, and then 
fitted to the curvature of the commutator. This is 
accomplished by wrapping a piece of light sandpaper 
around the commutator with the sand side out. With 
the brushes positioned, the armature is revolved sev- 
eral times until the brushes have become properly 
seated (see Figure 9-7, page 177). 

(c) Overload. Overloading of the starter will cause 
high currents in the brushes, resulting in overheating 
and burning. Overloading is usually encountered when 
the starter is run for periods longer than 30 seconds. 

(d) Dirty commutator. Oils, greases, and water will 
foul the commutator and cause excessive sparking be- 
tween the commutator and the brushes, thus causing 
high temperatures (see a. Possible trouble: Dirty com- 
mutator, page 163). 

(e) Loose connections. Loose connections cause added 
resistance, and consequently heat and sparking. All 
connections should be checked periodically for 

2. Repair. Burned brushes should be cleaned up, 
and if badly burned and worn, they should be replaced. 

To clean the brushes, they should be removed from 
the motor and washed in carbon tetrachloride. If the 
contact surfaces are filled with grease and dirt, they 
should be cleaned by reseating in the same manner as 
with new brushes; that is, by using sandpaper wrapped 
around the commutator. 

c. possible trouble: 


Weak insulation is a hazard, inasmuch as it is liable 
to cause short circuits. It is an indication that total 
breakdown of the motor is imminent. 

To check the insulation resistance either of the fol- 
lowing two methods may be used. It is possible to 
check the insulation resistance without disassembling 
the motor. To do so, it is necessary to lift or insulate 
the ground brushes so as to prevent current flow. It is 
also necessary to remove the power cable. 

(a) The megohmmeter method. This method is the 
most convenient, inasmuch as the megohmmeter, 
sometimes called a megger, is a self-contained unit that 
gives the resistance directly. The meter reads in 
megohms (1,000,000 ohms). 

In using the megohmmeter, one of its leads is con- 
nected to the power terminal and the other to the 
ground. It must be made certain that the ground 
brushes do not make contact with the commutator 
and that the power cable is removed. If there is a 
solenoid starting switch mounted on the starter, the 



megohmmcter lead should be connected after the 
switch. The second lead is connected to the ground. 

(b) The voltmeter method. This method is more 
intricate than the megohmmeter method. It requires 
some simple calculations, but will give satisfactory 
results. This method requires a d.c. power supply of 
about 220 volts, and a 500-volt voltmeter with a wind- 




Figure 9-1. 

Schematic diagram for checking 
insulation resistance. 

ing resistance of about 100 ohms per volt scale reading. 

The insulation resistance is found by using the fol- 
lowing equation: 

R-R (E '~ E} 

In this equation, Ri is the insulation resistance de- 
sired, in ohms, and Ru is the total resistance of the 

RM = rii x f M , when r M is the resistance per volt of the 
voltmeter, and p m is the full scale voltage of the volt- 

El is the line voltage and E the voltage read on the 
meter with the following hookup. Note that the 
ground brushes must be lifted and held off the commu- 
tator by a piece of insulating material. 

It is impossible to state what the exact minimum 
allowable value of insulation resistance should be. It 
depends entirely upon the particular starter, and the 
conditions under which the starter will be used. When- 
ever the resistance falls below 0.5 megohms (500,000 
ohms), the starter should be checked thoroughly. 
However, if it is needed to start the engine it will be 
possible to use it even when the insulation resistance 
falls below 0.5 megohms. 

1. Causes and prevention. Insulation failure is caused 

(a) Overheating. 

(b) Moisture. 

(a) Overheating. Operation of the starter motor for 

long periods of time will cause excessive heating of 
the coils and windings. Exceptionally high currents, 
often as high as 500 amperes, are encountered when 
starting. The starter should never be operated for 
periods in excess of 30 seconds. The motor should be 
allowed to cool for 2 minutes between each 30-second 
period of operation. 


220 V. 


«/ t " APPROX. 


Digitized by 

Go gle 

Figure 8-2. Wiring diagram for checking resistance of the 
insulation, voltmeter method. 

(b) Moisture. Water is probably the greatest de- 
teriorating factor to insulation and is usually respon- 
sible for insulation failures. Whenever a motor has 
become submerged, the windings, commutator, and 
brushes must be thoroughly dried before any attempt 
is made to operate the motor. To accomplish the 
proper drying of the windings after submersion, the 
motor should first be disassembled. If the motor was 
submerged in sea water, it must be rinsed off thor- 
oughly with fresh water before drying. 

Drying can be accomplished either naturally or by 
"cooking" in a warm oven. Caution: Do not let the 
temperature get above 180° F. If the moisture boils, it 
will damage the windings. Sufficient time should be 
allowed for all the moisture to be driven from the 
center of the windings. The drying process can be 
checked periodically by taking readings of the insu- 
lation resistance. 

2. Repair. Faulty insulation requires that the arma- 
ture or field coils be rewound. Direct shorts in the 
armature can be located by the use of a "growler." 
This method is discussed on page 178. Field windings 
may be checked for short circuits as outlined on 
page 178. 


8C1. General. There are four principal elements 
to be considered in discussing air starting systems: 




1. Compressor. 

2. Receiver or tank. 

3. Timing mechanisms. 

4. Air starting valves. 

8C2. Compressor. The air compressor requires a 
normal amount of attention if trouble and breakdowns 
arc to be averted. The air compressor has pistons, 
rings, cranks, and valves, as does the engine itself. 
Therefore, the compressor requires the same care and 
is subject to the same part failures as the main engine. 

a. possible trouble: 
compressor overheating 

Air compressors are either water cooled or air 
cooled. The construction and operation of the cooling 
system of a water cooled compressor very closely 
resembles the cooling system of the engine itself. 

Cooling troubles encountered in a water cooled 
compressor are discussed in Chapter 7. 

The air cooled type of compressor when overheated 
will operate at lowered efficiency, and increase the 
possibility of a compressor explosion caused by the 
combustion of the lubricating oil. 

1. Causes and prevention. Overheating of an air 
cooled compressor may be due to: 

(a) Cooling air flow restricted. 

(b) Cooling fins fouled. 

(c) Dirty air filter. 

(d) Restricted discharge. 

(e) Insufficient lubrication. 

(a) Cooling air flow restricted. Articles placed near the 
compressor will restrict the flow of air around it, and 
thus decrease the cooling by restricting the air supply 
to the fan. The fan must not be "choked" by placing 
boxes, cans, benches, etc., near it. 

(b) Cooling fins fouled. The cooling fins on all the 
cylinders, and on the inter and after coolers, must be 
kept clean. Oil and dust are good insulators and, if not 
removed, will restrict the amount of heat that can be 
transferred. This will cause the compressor to heat ex- 
cessively. The lower the temperature at which a com- 
pressor is operated, the .more efficiently it will operate. 

(c) Dirty air filter. The air intake filter must be kept 
clean. If the filter is allowed to become dirty and 
clogged, it will restrict the flow of air to the cylinder. 
This decreases the volumetric efficiency of the com- 
pressor which will necessitate running it for longer 
periods of time to develop the required pressure. 

(d) Restricted discharge. Restricted discharge valves, 
passages, and piping will cause higher pressures to be 
developed within the compressor cylinder. This re- 

Digitizeo by 

suits in higher temperatures and lowered efficiency. 
The discharge valves should be checked to see that 
they open fully. 

(e) Insufficient lubrication. Overheating may be due to 
lack of lube oil in the compressor sump. This causes 
excessive friction between the piston and cylinder, 
which greatly increases the rate of wear, and may pos- 
sibly cause the piston to bind in the cylinder. 

2. Repair. Overheating can usually be eliminated 
by correcting the conditions causing the excessive 

b. possible trouble: 
excessive belt wear 

Some compressors are driven by a series of V-belts. 
Excessive wear and deterioration of these V-belts is 
caused by: 

(a) Incorrect tension. 

(b) Oil and grease. 

(a) Incorrect tension. Improper adjustment will cause 
excessive wear of a V-belt. If too loose, it will 
cause slippage and loss of power. If too tight, it 
will cause excessive tension in the cords of the belt, 
resulting in early belt failure. Overtightening of the 
belt will also cause high bearing loads on the shafts 
of the motor and compressor, resulting in greater 
wear and early failure of the bearings. 

The belt tension should be checked at regular inter- 
vals. The correct amount of belt play is usually given 
in the instruction manual. If specific information is 
not obtainable, a general rule is to tighten the belt so 
as to allow a maximum of 1 inch to V/2 inches deflec- 
tion from its normal position (see Figure 8-3). 

Figure 8-3. Checking belt tension. 

(b) Oil and grease. Cleanliness is also an important 
item in belt life. Grease and oil will cause deteriora- 
tion of the rubber and separation of the cord. When- 
ever oil or grease is spilled or found on a V-belt, it 
should be immediately wiped off with a dry cloth. A 
cloth saturated in carbon tetrachloride, or naphtha, 
should then be used to remove all remaining lubricant. 

, Qrigiral from 



2. Repair. Worn belts must be replaced. It is advis- 
able to replace belts in sets when more than one belt is 
used. If only one of a set of belts is replaced, an exces- 
sive load will be placed on the new belt, since the old 
belts will have become stretched. An old belt in fairly 
good condition should always be saved. It may be 
combined with other used belts to make up a set at a 
later date. 

c. possible trouble: 


1. Cause and prevention. V-belts often develop a 
squeaking sound caused by the glazing of the belt 
surface. This trouble is not serious but may be a 
source of annoyance to the personnel. 

2. Repair. The squeaking of a belt can be eliminated 
by applying chalk to the belt's surface. The chalk acts 
as a mild abrasive to cut the glaze. Leather belt dress- 
ing has often been used, but is not recommended as it 
causes belt deterioration. 

When applying chalk, care must be taken to insure 
that the line switch is off. The fact that the compres- 
sor is not running at the start of the chalking is no 
guarantee that it will not start before the operation is 
completed. The switch must be off, and a sign to that 
effect hung upon it. 

The chalk can be applied by turning the compressor 
over by hand, letting the belts wipe over the chalk. 
Chalk should never be applied while the compressor 
is running. 

8C3. Receiver or tank. The receiver or storage 
tank requires only a minimum of attention. It should 
be drained daily to eliminate the collected condensate. 
Condensate reduces the compressor capacity. If water 
is allowed to collect without daily draining, it is 
liable to be carried over into the engine where it will 
cause considerable damage. 

a. possible trouble: 
sticking safety valve 

Each receiver is equipped with a safety valve to 
protect it from excessive and unsafe pressures. The 
safety valve is placed between the compressor and 
the receiver. 

The problem in this case is to detect faulty safety 
valves before they are called upon to perform their 
function. This requires that they be inspected and 
tested regularly at given intervals. The recommended 
interval is once a week. They should be checked by 
running the pressure up to the popping pressure set on 
the safety valve. This can be accomplished by holding 

Digitized by GQoQIC 

the automatic shutoff switch closed until the desired 
pressures are reached. 

1. Causes and prevention. 

(a) Improperly adjusted safety valve. 

(b) Corroded safety valve. 

(a) Improperly adjusted safety valve. Failure of the 
safety valve to open at the desired pressure may be an 
indication that the valve is improperly adjusted. It is 
customary to seal the adjusting screws and nuts after 
the safety valve has been adjusted. The seal should 
not be broken, nor the adjustment tampered with, 
unless it is desired to make an accurate and true ad- 
justment. The safety valve can be adjusted most 
accurately by use of a dead weight gage tester (see 
Figure 19-3, page 331). Whenever a faulty or im- 
properly adjusted safety valve is discovered, it must 
be corrected immediately. 

(b) Corroded safety valve. Moisture will often collect 
in the safety valve, causing a small amount of corro- 
sion. The small amounts of corroded material are 
usually blown out when the safety valve is tested, 
before they have any appreciable effect. It is necessary 
to check the valves periodically to see that they oper- 
ate freely. 

2. Repair. A faulty safety valve must be replaced 
immediately, or repaired. The compressor must not 
be operated if the safety valve is known to be faulty, 
unless a man is detailed to stand by the pressure gage 
to see that the pressure does not rise above a safe value. 

8C4. Timing mechanisms: general. There are sev- 
eral types of timing mechanisms. The function of each 
is the same, however. It is to admit the starting air to 
the proper cylinder at the proper time. There are three 
general classes of timing mechanisms, namely: 
Direct mechanical lift. 
Rotary distributor. 
Plunger type distributor valves. 

8C5. Timing mechanisms: direct mechanical lift 
type. This type system employs equipment similar to 
that found elsewhere on the engine, in that it uses 
cams, push rods, and rocker arms. These parts are 
subject to the same failures as are the corresponding 
major engine parts. 

a. possible trouble: 
improper adjustment 

1 . Causes and prevention . 

(a) Improper lift. 

(b) Improper timing, 
(a) Improper lift. The starting air cam should give 




raws \-' 

i he pmpcr lift to the air starting valve. When in the .surfaces- cadi he: checked by u.un.g a rhjn Coattng of 

on posiri6n r therrs mitsr be .clearance hex w cert -'the Cum 
and the cam v 

aJvc foil a we:. I 
mamtajned, hoc treses wUf jflow by the: valve scat on 

vastves. Plunger ryfx djumhiuor valves, as used On 
rhcr Cbdjtcf-Bess^nicr ami Hamilton dicse) engines. 

„. „ r *. ro ^ ok .ode s^s^r rz^-xs 

nuTis are. ti^nt/ v- || 

■ (bX Tmpriper. ixmni. The. time jit which the air tollow » 

fb) Improper; &mi% 

s?arc% valve opens in the engine Cycle is very import " Af }H)ssi b l t t rdu n l b ; 

cant if the maximum starting power \% to be^fcuined sruc-fc LHSTiuauToa valves 

from Xht sorting a«r . At, the lobes tfl the starting air — — ~— — — ~ 

2. R^air. The engine io$rructiOQ maouai should be 
consulted for die proper values o£Uft ? rapper clear- 
ance v and time of valve •opeoing' v "A?j)u^tmcnts-.hihouk! 

be made amy as specihed in the manual. Causes of '^3^ 
derangement oi the actuating geai iua>: be fouad under 
the headings coveting similar parts of the major 

, . ■ ' 


8C6. HmV 

rotarv disrrihutgf, as Used on:- the Alco, Fairbanks-" 

iNtHI-kVrivh DtSTRHHTOit 

— — :„: — = — - ' - - • — . . ^ Vf- . ^r^ . .; . ? ; - . -'^^^^^Bh 

• ' ' ' \ ■ . . ■ ' 

1 Ca,,«> *W pennon. Wbe„ Jifticuit.e. .re en- ^ 
red w<rh die rotary air starting disitibator, the 

counter c 






1 ; 


> : 

5SS9 • * 

. ! • 

presem ^ a luhnonr And a seal.. 

rence of *tieh resinous deposits, the receiver or air 
sbotiid be drained daily alone with ail 


can often be corrected by increasing the initial tension. 

(d) Actuating pressure not released. Should the air 
passages become clogged or restricted, it is likely that 
the valve will hang open or be sluggish in closing. 
This is apt to allow the combustion gases to back up 
and into the air passageways, causing the valve sur- 
faces to become burned and incapable of maintaining 
a tight seal. 

2. Repair. The upper piston can usually be relieved, 
without removing the valve, by using light oil or 
diesel fuel, and working the valve up and down. In 
severe cases, the valve will have to be completely 
disassembled and cleaned. When such methods are 
used to relieve a sticking valve, every precaution must 
be taken to insure that the valve surfaces are not 
burned and deformed. The air lines should be wired 
out to insure that they are open. The distributor or 
pilot valve assembly should then be checked to be sure 
that the proper relief can be effected. 

b. possible trouble: 
leaking air valve mechanical lift 

The air valve usually is located in the cylinder head. 
When it leaks, it will cause hard starting, and often 
sufficient loss of air to prevent starting. It will also 
allow combustion gases to enter into the valve body 
while the engine is running. This will cause further 
damage to the valve and valve seat. Leakage occurs 
not only between the valve and cylinder chamber, but 
also past the packing around the valve stem. 

1 . Causes and prevention . 

(a) Packing nut overtightened. 

(b) Insufficient spring pressure. 

(c) Obstruction between valve and seat. 

(d) Bent valve stem. 

(a) Packing nut overtightened. In an attempt to stop 
minor leakages of air around the valve stem while 
starting, the packing nut is often overtightened. Fre- 
quently this prevents the air valve from seating and 
allows leakage from the cylinder into the valve while 
the engine is running. The packing nut should never 
be tightened excessively. 

(b) Insufficient spring pressure. Occasionally the re- 
turn springs on the valves are unable to return the 
valves to the seats after admitting the air charge. This 
may be caused by a weak or improperly adjusted spring. 

(c) Obstruction between valve and seat. If a particle of 
dirt, carbon, or other material becomes lodged between 
the valve and valve seat, it will allow combustion 
gases to pass. This action will cause the valve and 
seat to burn, and a leak to start. 

(d) Bent valve stem. If the valve stem becomes bent, 
it will cause the valve to bind and hang open. The 
stem is usually bent by careless handling during 

2. Repair. When the valve is found to be leaking, it 
should be completely disassembled and inspected. All 
carbon and gum deposits should be removed with a 
special Carbon and Lacquer Removing Compound, 
Fed. Std. Stock Cat. No. 51C-1567-56. The stem 
should be checked to see that it is not bent. Particular 
attention must be given the surfaces of the valve and 
valve seat. If they show signs of scoring or discolora- 
tion, they may be polished by lapping them together 
with a fine lapping compound. Jewelers' rouge or 
talcum powder with fuel oil are suitable lapping 

Digitized by GOOSES 




The oi'»citv uf j b,.crccv c, 

batocxy can deliver at a particular r*tc "of ■discharge. 

rent cotitiouousi'v for 10 liours, Ifihe battery is force J 
to deliver 20 amperes continuously, the duration of the 
discharge, vviii be less than 5 hours because rhe capac- 
ity of "Che *(0r»gc battery is fc»s at higher rates oi 

.In electrically started diesel installations, it »s cus- 
ternary m charge the batteries during operation by 
forcing current through the batteries from a small 

ftewv T*p«olh*rd bottery L ~~ ~ 

ct v /^-^Li ' .,1^1, r,.r«.*W'»i rh<* DEAB BATTERY : 

stamped *irh a name plate winch hirmshes to the _ — — ^ — _ 


be replaced by recharging the battery if the battery is 
to continue in service. 

If the small charging generator driven by the diesel 
engine is not operating properly, that is, if it is not 
delivering current at a sufficiently high rate between 
engine starts, the charge withdrawn from the battery 
during the starting period will be greater than that 
replaced by the generator during the charging period. 
This usually occurs when an auxiliary diesel engine is 
started and secured at frequent intervals. In such cases, 
the charging period is not sufficiently long to keep the 
battery from running down. Batteries also run down 
when the engine is allowed to stand idle for extended 

The voltage regulator should be set so as to provide 
a sufficiently high charging rate to keep the starting 
battery from running down rapidly. It must not be 
set so as to cause charging at a higher rate than that 
specified on the battery name plate, as this will cause 
damage to the battery. The correct rate of charge is 
that which will maintain the specific gravity of the 
battery at about 20 points below the normal fully 
charged gravity. 

Even with proper setting of the voltage regulator, 
the batteries used for starting may have to be charged 
periodically by an outside source of current. Periodic 
observations of the specific gravity will indicate when 
there is need for charging. Specific gravity readings 
should never be taken immediately after adding water 
to the battery, as the water will float on the surface of 
the electrolyte and give a low gravity reading. Like- 
wise, if the gravity reading is taken when the electro- 
lyte level is low, the reading will be erroneously high. 

(b) Damage to plates. If the plates become sulphated, 
short circuited, or if their active material is dislodged, 
the capacity of the battery will be greatly reduced and 
it will become discharged after little service. If such 
a condition is suspected, the battery should be re- 
moved from service and the condition of each indivi- 
dual cell checked. When a bad cell is located, the 
battery should be retired from service and the cell 

Prevention of damage to plates consists of observing 
the following precautions: 

(1) The electrolyte should always be maintained at 
the level specified on the battery name plate. Evapo- 
ration losses should be replaced by adding only pure 
distilled water. If the plates are allowed to stand 
uncovered by electrolyte, they will dry out and be 

(2) When adding water to the battery, only pure 
distilled water should be used. Extremely small quan- 

Digitized by GO file 

tities of impurities in the water will quickly ruin the 
plates by local action. 

(3) The battery should never be allowed to stand in 
a completely discharged condition for more than 24 
hours, as this will cause sulphation. 

(4) Acid should never be added to the electrolyte 
unless it is definitely known that acid has been lost. 
Low specific gravity after charging may indicate 
sulphation. Adding acid to the electrolyte will in- 
crease the seriousness of the damage. 

(5) The battery must never be charged at a higher 
rate than the finishing rate specified on the battery 
name plate. Charging at excessive rates is undesirable 
because it may result in excessive electrolyte tempera- 
tures and gassing. The rate of charge is determined by 
an ammeter in series with the battery being charged. 

(6) The battery electrolyte should never be allowed 
to attain a temperature above 125° F. For this reason 
the battery should not be stored in any compartment 
where the temperature exceeds 100° F. Charging at 
excessive rates will also cause overheating. Electro- 
lyte temperatures must be observed at intervals during 
charging to insure against overheating. 

(7) Violent gassing must also be avoided. When 
current is supplied to the battery at a high rate, some 
of the water (H 2 0) in the electrolyte is decomposed 
into hydrogen (H 2 ) and oxygen (0 2 ). These gases are 
liberated in the exact proportion to form one of the 
most powerful explosive mixtures known. In addition 
to the obvious danger of explosion, there is a strong 
probability of damage to the plates. The small bubbles 
of gas may be liberated with sufficient violence to 
dislodge the active material from the plates. This ma- 
terial will fall to the bottom of the cell, reducing the 
capacity of the battery. If the dislodged material 
accumulates on the floor of the case to such a height 
that it contacts the bottom of the plates, a short cir- 
cuit between the plates can result and thereby make 
the cell inoperative. 

(c) Improper starting procedure. The life of starting 
batteries, between charges, may be considerably in- 
creased by using the proper procedure for starting the 

The following precautions should be observed in 
starting to avoid unnecessary drain on the battery: 

(1) An unnecessarily high viscosity lubricant should 
not be used in the engine crankcase. When the lubri- 
cating oil becomes thicker, that is, more viscous, due 
to low temperature, the required cranking torque will 
be greatly increased. When starts are made under very 
cold conditions, a special lubricant, called a high 
viscosity index lubricant, whose viscosity is not greatly 

Original from 


affected by temperature, may be required. It should be 
remembered that the capacity of the battery is de- 
pendent upon the battery temperature. As the temper- 
ature decreases, the battery capacity also decreases. 
Hence, every available aid to starting should be em- 
ployed in cold starting. Many engines provide some 
form of air heater to aid in starting under cold condi- 
tions. When such devices are furnished, the operator 
should maintain them in good condition at all times. 

(2) The instructions of the engine manufac- 
turer for starting should be followed, but in no case 
should the starter switch be depressed for more than 
30 seconds. After a 30-second attempt, the battery 
must be allowed to "rest" for at least 2 minutes before 
again attempting a start. This rest period avoids 
overheating the battery and allows any gas bubbles 
which may have blanketed the plates, thus insulating 
them, to disperse. The rest period also gives the oper- 
ator an opportunity to check the engine for possible 
mechanical difficulties or oversights that may be pre- 
venting a quick start. (See Chapter 1, Section B, for 
possible causes.) Only in rare instances should engines 
fail to start within 30 seconds unless there is some fault 
in the procedure or the mechanism. Worn rings, leaky 
valves, or other factors which tend to reduce compres- 
sion pressure greatly interfere with starting. 

2. Repair. A dead battery may normally be placed 
in operable condition by recharging. Full instructions 
for charging batteries will be found in the Bureau of 
Ships Manual, Chapter 62, Section II. 

Generally, Navy storage batteries may be charged 
by any direct current source which may be regulated 
to provide a charging rate of the magnitude indicated 
on the battery name plate (see Figure 9-3). A lower 
charging rate may be used, but the batteries must be 
left on the line longer. The charging rate shown on 
the name plate, however, must never be exceeded as 
this endangers the battery. Violent gassing, or tem- 
peratures above 125° F, must never be allowed to exist. 

Charging should be terminated when the normal 
specific gravity of the electrolyte has been attained. 
The electrolyte must be at the proper level, and thor- 
oughly mixed, when taking readings. 

b. possible trouble: 
rapid loss of electrolyte level 

This trouble becomes apparent when, upon making 
the periodic "watering" round of the starting bat- 
teries, one or more cells are found to have an abnor- 
mally low electrolyte level as compared to other cells 
in comparable service. 

Digitized by GOuQIC 

1. Causes and prevention. Rapid loss of electrolyte 
level is generally caused by: 

(a) Cracked case. 

(b) Failure to replace filler caps. 

(c) Excessive gassing. 

(a) Cracked case. Small cracks in the side of the bat- 
tery case will permit the electrolyte to seep out and be 
lost. Cracks in the top of case will allow the electro- 
lyte to be sloshed out. In addition to the ill effect of 
lost electrolyte, there will probably be considerable 
corrosion of terminals and lugs. 

The case must be inspected carefully for cracks when 
rapid decline in level occurs. 

Cracks may result from rough handling or improper 
storage. The battery should never be allowed to 
stand in a totally discharged condition. Among other 
undesirable effects, this increases the danger of freez- 
ing. Likewise, a battery that has been freshly watered 
should be protected from the cold. If it is not, the 
water, which at first tends to float on the electrolyte, 
may freeze and cause breakage of the plates, separators, 
and case. 

(b) Failure to replace filler caps. Filler caps are vented 
to permit pressure within the battery to be equalized 
with that outside. This vent, however, is small 
enough to prevent much evaporation or spilling of 
electrolyte. Filler caps should always be screwed 
tightly in place while the battery is in service or being 
charged. The vent holes must not be allowed to be- 
come plugged. 

(c) Excessive gassing. Batteries on charge will begin 
to emit gases, hydrogen and oxygen, during the latter 
part of the charging period. The high electrolyte 
temperature resulting from a high finishing rate of 
charge causes rapid evaporation of the water in the 
electrolyte. Although some water will be consumed by 
decomposition, considerably more will be lost by 
evaporation. Violent gassing must not be permitted, 
as it tends to loosen active material. The electrolyte 
level must be observed carefully throughout the 
charging period. 

2. Repair. Low electrolyte level, if due to loss of 
water only, may be remedied by the addition of pure 
distilled water to the battery. However, if consider- 
able acid has been spilled it will be necessary to fortify 
the electrolyte by addition of dilute acid. The battery 
should first be fully charged. Then, dilute sulfuric 
acid should be added in small quantities until the 
specific gravity of the electrolyte, with the electrolyte 
at the proper level, is as desired. If too much acid is 
added, a portion of the electrolyte must be replaced 
with distilled water. 




— ~, — — - - — — with die -purpose of makings 'much surfticc of contact 

.c posst6tB Tuot'B!£. as posssbfc between tb<r lug and rermrnai, 

. CORROSION OP BATTERY TERMINALS Where COTOSl'tfll is CvidjtlU, it IS aJvWVS good pdjCy 

~' - : ;7 "7 "*""7 7 , """" to replace rife 'log holts, « corroded bolt* may subsc* 

This trouble .is recoe-nized bv tuning BetefiOratioo. , i ._ > , ... t ' « .. i . ... ♦...„." 



green .and white scale usually cavers the tenn in 

lugs, cables/and tbs'case in t&J vicinity of the ter- 
minals. This $cate makes it difficult to loosen the 


[*) Cordis warning Overfilling of cells when adding 
water, or sJoshiag.eJectro.lyte out when jmidluig the 
battery will allow the electrolyte toconiacr terminals, 
cable; etc. Care should be taken to avoid drm\ 

O) yCmltsjinm whtU ttikm& w%r. Wkii the 
hydrowter »d4 thermo^c^ ^ used, the operator 
shotfJJ be cartful nor ic- ^.io-v electrolyte to drip onto 
the battery. The loss of electrolyte,, because -of the 
, i* Undent?}?, as t.\ the resultant corn*-" 

retmmal and iug surfaces. The small pouns that do have been an charge aud, gassing-. 


(c) Alio\vi 

GO Cbar£ih% itfMvtritUateit i'unparTHKMf ..'If ikt bat- 
teries aire charged in confined spaces, the hydrogen axid 

x U) nlknvmt: ■ oosecoitriT;ci-;«-»ni; or short cecums. 

I ■ MM. ; 

■ - - ■• • 


The lug holt* musi be kept tight 

and there nuv not be sufficient contact area to pass the switch, or from a ropi srruefc against a 
required starting current. mefeL surface, will cause a wkkk **plc*tori. : 

1 tight The holts should All batter*/ "charging compartments musr be va*- 

|%c will not allow complete surface cooler- *«n ■ - • .In an emergency .whin ventilation o W! be pro- 
though chs. lug boic> lire tightened properly This vided, batteries should, be charged on deck. 


charged. Charging must be ceased if work on con- 
nections is necessary. 


9B1 . Generators. The generators under considera- 
tion are those used as auxiliaries to the engine in order 
to maintain the charge on the starting batteries. 

a. possible trouble: 
generator not charging — defective generator 

The first indication of a faulty generator is a low 
battery charge together with a zero ammeter reading 
when the engine is running. A zero ammeter reading 
alone does not indicate generator failure, however, for 
when the batteries are fully charged the function of 
the voltage control regulator is to limit the generator 
charging rate. 

To eliminate the possibility that the trouble is in 
the generator control unit, the following procedure 
should be observed: The cover is first removed and a 
check made for any loose connections or burned 
points. With the engine running, a short jumper wire 
is connected between the terminal marked bat and the 
terminal marked gen (or a for armature, as the case 
may be). The engine speed is brought up, and the 
ammeter is checked to see if the generator is charging. 
If it is charging, the trouble will probably be in the 
cutout relay rather than in the generator itself. If the 
generator still does not charge, the jumper wire 
should then be placed so as to make certain the field 
terminal is grounded. This is done by running the 
wire from a good ground to the generator terminal 
marked f or field. If the ammeter still shows no 
charge, it can be assumed that the trouble lies in the 
generator, and the field and armature will have to be 
examined separately. If the generator docs charge 
with the field terminal grounded, it indicates that the 
voltage or current regulator is at fault. 

1. Causes and prevention. Failure of the generator to 
charge the batteries can be attributed to one of the 

(a) External wiring. 

(b) Faulty drive. 

(c) Faulty brushes. 

(d) Faulty commutator. 

(e) Faulty armature. 

(f) Faulty field coils. 

(a) External wiring. All external wiring and connec- 
tions should be checked. Due to the vibration to 

which the generator is subjected, broken and loose 
wires are quite probable. Lock washers under all 
terminal nuts and screws will assist in preventing loose 
connections. Adequate support for the wires must be 
provided, and they must not be expected to perform 
any function other than that for which they arc 
intended. No electrical wiring should be expected to 
perform the functions of a clothesline. 

(b) Faulty drive. On positive drive generators, a 
check must be made to see that no shaft keys are 
sheared and that all shafts are intact. This can be done 
quickly by removing the commutator cover and ex- 
posing the armature, pressing the starter button, and 
observing whether or not the generator shaft is turn- 
ing. If it does not turn, the generator drive must be 
disassembled and checked for broken parts. 

7 ' 


Figure 9-6. Checking belt tension. 

On V-belt drive generators, the belt must be checked 
both for wear and proper tension. Correct belt tension 
should allow 1- to lJ/2-inch belt deflection on each side 
of the neutral position (see Figure 9-6). A belt improp- 
erly adjusted will wear rapidly, and if loose, will 
allow slippage. 

(c) Faulty brushes. The brushes must be inspected 
for cleanliness. At least 75 percent of the brush surface 

f*6202°— 46— 13 

Digitized by 

Go gle 


Figure 9-7. Sanding a brush. 

Origiral frcrn 


must be in contact with the commutator. If the 
brushes need dressing, a narrow strip of 4/0 sandpaper 
wrapped around the armature as shown in Figure 
9-7 should be used. Caution. Emery paper must never 
be used, for the abrasive is an electrical conductor and 
will short circuit the commutator bars if it lodges be- 
tween them. Sufficient spring force must exist to hold 
the brush securely on the commutator, and the brushes 
must be free to move in the holders without binding. 
The spring force should be between 15 and 22 ounces 
on each brush. 

(d) Faulty commutator. The commutator must be 
clean. If dirty, it will impede the current flow by 
adding greatly to the circuit resistance. The commu- 
tator should be cleaned either with a dry cloth or 
6/0 sandpaper. 

(e) Faulty armature. To check an armature, it is 
necessary to disassemble the generator completely. 

The armature is checked for shorts by using a 
growler. Growlers work on the same principle as an a.c. 
transformer without a secondary coil. The armature, 
when placed in the tester, acts as the secondary (see 
Figure 9-8). The armature is placed on the growler as 
shown in the figure. If there is any short circuit in the 
windings, such as a shorted coil or two commutator 
bars, the armature core will become heated and 
strongly magnetized, and will attract a strip of steel 
held over it, such as an old hack-saw blade. The 
armature is rotated slowly until a position is obtained 
where a pull on the steel strip is felt. If such a position 
cannot be found, it may be assumed that the armature 

is not shorted. If a short is found, it should be made 
certain that it is not caused by material caught be- 
tween the commutator bars. A hack-saw blade should 
be used to clean the slots. 

Open armature circuits can be found by checking the 
resistance between adjoining commutator segments. 
The values of resistance should not vary more than 
15 percent. 



Figure 9-8. Testing an armature on the growler. 

Digitized by 

Go gle 


Figure 9-9. Preparing to test for polarity of field colls. 

(f) Faulty field coils. The coils should be checked for 
shorts. Both field coil leads should be disconnected, 
and one of them attached to the battery lead and the 
other to the generator body (see Figure 9-9). The 
battery voltage should be about 34 rated generator 
voltage. If there are no shorts in the field circuit, 
there should be no current flowing, and consequently 
no sparking when connections are made. The coils 
should next be tested to insure that there arc no 
breaks in the windings. This is done by touching the 
second lead from the battery (the one formerly 
grounded) to the second field terminal. There should 
be a small spark when the connection is made. If no 
spark occurs, it indicates that the field ciruit is open. 

2. Repair. Repair of the armature and the field coils 
is not possible unless a fully equipped electrical shop 
is available. The usual practice is to replace either the 
defective parts or the entire generator unit. If a com- 
plete generator is available for installation, it should 
be installed on the engine. The defective generator 

Qrigiral from 


should then be sent to a fully equipped shop for rcpair 
and held as a spare until needed again. 

9B2. Generator controls. Control units for gener- 
ators are usually composed of three separate sections. 

First is the cutout relay. All generator controls have 
a cutout relay. The cutout prevents current from flow- 
ing into the generator when it is not charging. If the 
generator were not equipped with a cutout, the cur- 
rent from the battery would attempt to run the genera- 
tor as a motor, thus heating the coils and discharging 
the battery. 

Second is the voltage control. The function of the 
voltage control is to reduce the charging rate as the 
batteries become charged. The voltage control pre- 
vents overcharging. 

Third is the current regulator. The current regulator 
limits the charging rate of the generator when the 
batteries are low. This safeguards the windings, 
commutator, brushes, and the batteries from heavy 
charging currents. 

In general, the generators are shunt wound (the 
field in parallel with the armature circuit). The field 
exciting voltage is often taken from the commutator 
by a third brush which is adjustable as to its position. 
Other generators use the full armature voltage, and 
control the basic charging rate by means of variable 
scries resistances placed in the field circuit by the 

Figure 9-10 is a diagram of a typical control unit. It 
is customary to mount all three sections on one base. 
The cutout relay is connected in the armature circuit 
between the generator and the battery. The voltage 
and current regulators are in the field circuit and thus 
regulate the field strength and the output. 



Figure 9-10. Wiring diagram of current and voltage regulator. 

a. possible trouble: 

generator improperly charging 

control unit defective 

Trouble with the individual sections of the control 
unit can be found as outlined on pages 177-178. 

1 . Causes and prevention. Improper generator control 
is due to improper functioning of: 

(a) Cutout relay. 

(b) Voltage regulator. 

(c) Current regulator. 

(a) Cutout relay. A defective relay will prevent the 
generator from charging the batteries. The usual 
trouble is that the contacts become fouled and burned 
so that they cannot conduct the current. 

(b) Voltage regulator. A defective voltage regulator 
will allow the generator to overcharge the batteries 
and cause excessive heating of the generator field and 
armature windings. 

(c) Current regulator. A defective current regulator 
will allow the armature windings to overheat. 

2. Repair. Should the trouble lie in the cutout relay, 
the following procedure should be used. First, the 
contact points should be cleaned. A spoon or rifller file 
should be used on concave surfaces, and a flat file on 


Digitized by 

Go gle 



Figure 9-11. Cleaning contact points. 

convex surfaces (see Figure 9-11. No more material 
4 should be removed than is necessary to clean the sur- 
faces. Sandpaper or emery paper should not be used. 
Care must be taken when filing the contacts not to 
bend or distort the supports. Second, the contact gap 
must be adjusted. This is usually done by adjusting 
the armature stop. The proper gap is .020 to .025 
inches. The proper value for a particular generator 
cutout relay should always be obtained from the 
manual. Third, the closing voltage must be adjusted. 
This is done by varying the spring tension on the 
armature. To check the closing voltage and to make 
the adjustments, a voltmeter should be connected 

Origiral frcrn 


across thc armaturc. After the generator has been 
brought up to speed, the cutout should close at a volt- 
age within the amounts given in the table below. 

System Closing Range 

6-volt, 3-ccll 6.2 to 6.8 volts 

12-volt, 6-ccll 12.4 to 13 4 volts 

24-volt, 12-ccll 25.5 to 27 0 volts 

30-volt, 15-cell 32.0 to 33. 5 volts 

32-volt, 16-ccll 34.0 to 35 5 volts 

The spring tension is increased to increase the clos- 
ing voltage. If the armature relay tends to vibrate at 
low engine speeds, it indicates that the closing voltage 
is too low. This can be corrected by increasing the 
spring tension slightly (see Figure 9-12). 











Figure 9-12. Cutout relay adjustments. 

There are three things that are most likely to cause 
trouble in thc voltage regulating section of the control 
unit. Thc points can become burned, which causes 
poor contact and results in increased field resistance 
and lowered output. Thc coil wire and resistance can 
burn out; their failure may also result in lowered out- 
put or may cause the field to break down completely. 
Finally, improper spring tension will cause the maxi- 
mum charge on the battery to be cither too high or too 
low, depending on whether the spring tension is too 
great or too small. 

When servicing the voltage control, the contacts are 
first cleaned with the proper file. All filings must be 

blown out of the unit; being of metallic nature they 
will cause short circuits if they become lodged between 
thc contactors and other parts. The gap between the 
core and the armaturc must be correctly set. The usual 
air gap is .065 to .075 inches, but the instruction manual 
should always be consulted for a particular control. 
Thc regulated voltage must next be determined. 
This must be done with the control unit and the gener- 
ator at normal operating temperatures. This is done 
by first disconnecting the wire from the battery ter- 
minal (sometimes marked ammeter) of thc control 
unit. A voltmeter should then be placed between the 
armature terminal of the generator and the ground 
(sec Figure 9-13). The engine should then be started 
and brought up to speed. 




Digitized by 

Go gle 

Figure 9-13, Voltage regulator adjustments. 

The voltage at which thc voltage regulator takes 
effect should be noted. This can be done by observing 
thc opening, or vibration, of thc voltage control 
points, and thc dropping of thc voltage. Thc voltage 
at which thc regulator should cut in, and above which 
thc charging voltage should not rise, is dependent 
upon thc nominal voltage of the system and thc de- 
sired charging rate. 

Thc following values are given for the general sys- 
tem. They should be used only in the event that thc 
manual for thc particular voltage control in question 
is not available. 

System Cut in Range 

6-volt, 3-ccll 7.2 to 7-7 volts 

12-volt, 6-ccll 13.5 to 15.0 volts 

24-volt, 12 cell 27.5 to 30.0 volts 

30-volt, 15-cell 35 0 to 39.0 volts 

32-volt, 16-ccll 38.0 to 42.0 volts 

The mechanical construction of the current regulator 
is usually similar to that of the voltage regulator, but 
with one principal difference. The actuating coils of 




the voltage regulator are across the armature circuit; 
the actuating coils of the current regulator are in series 
with the armature. Casualties to the current regulator 
are similar to those of the voltage regulator. 

In servicing the current regulator, the contacts arc 
first cleaned with the proper file. All filings and dust 
must be blown out. The air gap must be set. The cor- 
rect value for the gap should be obtained from the 
operating or maintenance manuals. If no manual is 
available, the usual value may be taken to be between 
.070 and .090 inches. This adjustment is made by 
changing the armature stops. The regulating voltage 
must also be checked. To do this, the charge on the 
batteries must be low, or suitable means used to reduce 
the battery voltage, such as using one or two fewer 
cells in the battery circuit. The lead from the control 
unit to the battery must be disconnected, and an am- 
meter connected in the line. A jumper lead should be 
placed across the contact points as illustrated in Figure 
9-14. The engine should then be started and brought 
up to speed slowly, while observation is made of the 
ammeter and the contact points of the current regu- 
lator. At the regulated current value, the contacts will 
vibrate. The jumper wire should then be removed and 
the ammeter reading again observed. The proper 
setting for the current regulator is dependent upon the 
rating of the generator. The correct value should be 
obtained from the instruction manual. If this infor- 

Figure 9-14. Current regulator check. 

mation is not obtainable, the data from the generator 
name plate should be used. The current regulator 
should be set at 100 percent rated current. The rated 

Digitized by GQoQIC 

current is calculated by dividing the rated power 
(watts) of the generator by the rated voltage. To in- 
crease the controlled current, the spring tension should 
be increased. 


9C1. General. Electrical relays and contactors arc 
used chiefly in the starting circuit to control the elec- 
trical starting motor. The contactors are subjected to 
extremely high currents and must be maintained in 
good condition. These contactors are either of the 
manually operated type or the magnetically operated 
type. Starting relays and contactors are designed to be 
operated for only short periods of time. 

a. possible trouble: 
burned contacts 

Burned contacts cause increased resistance in the 
starting circuit, lowering of the efficiency, and finally, 
complete failure of the circuit. 

1. Causes and prevention. Factors resulting in burned 
contacts are: 

(a) Normal wear. 

(b) Switch not held down firmly. 

(c) Using the starter to jack the engine. 

(d) Cranking for periods longer than 30 seconds. 

(e) Low battery voltage. 

(a) Normal wear. Under continued use, the contact 
points will become burned and worn. When this con- 
dition exists, the contactors must be replaced. The 
general construction of the contactor unit is such that 
this necessitates the replacement of the complete unit. 

(b) Switch not held down firmly . Burned contact points 
can often be attributed to the fact that the operator 
does not hold the operating switch closed securely 
when cranking the engine. This allows the current to 
arc across the contacts and develops excessive heat 
which will destroy the surfaces. When starting an en- 
gine, whether the contactor be manual or magnetic, 
the button must be held down firmly. 

(c) Using the starter to jack the engine. The practice of 
using the starter intermittently to jack the engine over 
is responsible for a great deal of starter motor and con- 
tactor troubles. When timing, and making other en- 
gine adjustments, the engine should be jacked over 
by hand with the jacking gear provided. 

(d) Cranking for periods longer than 30 seconds. Crank- 
ing for periods longer than 30 seconds should be 
avoided. Whenever a starter is operated for a period of 
30 seconds, a period of 2 minutes must be allowed 
before again using the starter. 

Original from 



(e) Low battery voltage. This is one of the major 
causes for burned contacts and burned motor insula- 
tion. 1 1 will cause faul ty solenoid operation by allow- 
ing the solenoid to vibrate and arc excessively. 

2. Repair. If contacts are burned, but there is still 
material left, they may be cleaned by using a convex 
file. Some relays have removable contacts, in which 
case they can be removed and wire brushed. If a new 
set is available, however, it should be installed. 

b. possible trouble: 
magnetic device fails to engage 
pinion and close circuit 

Certain types of magnetically operated devices per- 
form the functions of engaging the pinion of the start- 
ing motor with the ring gear on the flywheel, and 
closing a set of contacts in the starting motor circuit. 

1. Causes and prevention. Failure of this device to 
function properly may be due to: 

(a) Low battery charge. 

(b) Sluggish pinion spline. 

(a) Low battery charge. A low battery charge will pre- 
vent the solenoid from developing sufficient force to 
engage the drive pinion. 

(b) Sluggish pinion spline. The force developed by 
the solenoid is limited, and if the force required to en- 
gage the drive pinion is too great, or if the solenoid 
fails, it will be impossible to start the engine. In 
emergency cases, however, the pinion can usually be 
engaged and the contact closed by hand. Factors that 
affect the mechanism are: heavy grease which, when 
cold, adds appreciable drag; burrs on the shaft; defec- 
tive wiring or push-button switch. 

Sluggish action of the pinion mechanism can be pre- 
vented by using only light oil as a lubricant instead of 
heavy grease. Normal care will prevent burring, 
which frequently occurs when the motor unit is dis- 
assembled or reassembled. 

2. Repair. The engaging mechanism should be 
cleaned with solvent or diesel fuel, dried, and sparingly 
oiled. Grease should not be used, particularly when 
the engine is subjected to low temperatures. 

Any burrs found on the spline or other parts should 
be dressed down carefully with a file or small stone. 
The unit must be cleaned carefully after filing or 

The switch at the instrument board is subject to the 
same troubles as the solenoid operated device. How- 
ever, the conditions are usually less severe due to the 
fact that lower currents are handled. When the solenoid 

Digitizes by CjOuQle 

fails to operate, the wiring and the switch at the 
board must be checked. 

Occasionally the solenoid coil will burn out, but 
this is rare. If the coil is found to be defective, the 
entire solenoid unit must be replaced. 


9D1 . General. Wiring on the diesel engine is not 
extensive. Nevertheless, the wires that are used re- 
quire a certain amount of care if the following troubles 
arc to be avoided 

a. possible trouble: 
burned insulation 

1. Causes and prevention. Burned insulation is in- 
variably the result of neglect and carelessness on the 
part of the operators. Burned insulation will result in 
short circuits with the added possibility of fire or 
crippling of the engine. Most engines are equipped 
with framework or metal looms to support the wiring. 
These should always be used as they prevent excessive 
flexing of the wire. The loom provides protection 
from grease, oil, and water. 

Care must be taken to prevent the wires from coming 
into contact with hot surfaces, particularly the ex- 
haust manifold, as the temperatures there are sufficient 
to cause immediate destruction of the wires. Other 
surfaces, while not hot enough to cause immediate 
destruction of the wires, will accelerate the deteriora- 
tion of the insulation. Wires protected by a metal con- 
duit, such as pyrometer leads, should not be allowed 
to come into contact with hot surfaces any more than 
wires protected only by rubber and fabric. Metal, 
being a good conductor of heat, will quickly transmit 
the heat to the interior where it will cause the insula- 
tion to deteriorate. 

2. Repair. Repair to burned insulation should not 
be made; instead, the wire should be replaced. When 
replacing wiring, be sure that the proper size of wire is 
used. If the proper size is not available, take steps to 
procure it. In the meantime, the insulation can be re- 
stored by using both rubber insulating tape and fric- 
tion tape. The rubber tape should be applied first, 
stretching it out tightly. It should then be covered 
with two layers of friction tape. If the repair will be 
subjected to oil and water, it can be given a coat of 
shellac or varnish, the latter being the more desirable, 
though it takes much longer to dry. 

When replacing wiring, it is not only important to 
use the proper wire but also to make the connections 
correctly. If several wires are involved, the wires and 

1 Qrigiral from 



terminals should be tabled when disassembling in 
order to eliminate the possibility of errors when 
reassembling. Terminal lugs should always be used. 
The old ones can usually be reused. If, on smaller 
wires, no lugs are available, solder applied to the end of 
the wire will hold the strands together when the 
terminal screw or nut is brought down on it. 

It is always advisable to replace the wires which arc 
in a conduit, rather than repair them. It is impossible 
to inspect the repairs or to ascertain their condition 
when within the conduit. Also, the repair is usually 
larger in diameter than the undamaged insulation, 
which makes it difficult to get the repaired portion 
into the conduit. 

If it ever becomes necessary to make a splice, the two 
or more wires should be treated in the following man- 
ner. The insulation should be stripped for a distance 
of about six to eight times its outside diameter, and 
the metal well cleaned by scraping. The strands are 
then twisted together and soldered. The insulation 
should be restored by using both rubber and friction 
tape, and shellac or varnish, if considered necessary 
(see Figure 9-15). 

H— G to a d 


^^^ ^ 



Figure 9-15. Making a wire splice. 

B. POSSIBLE trouble: 

1. Causes and prevention. 

(a) Burned insulation. 

(b) Deteriorated insulation. 

(c) Failure to strip armored cable properly, 
(a) Burned insulation. Short circuits arc always asso- 

Digitized by 

Go gle 

ciated with burned and defective insulation. See 
a. Possible trouble: Burned insulation , page 182, for a 
further discussion. 

(b) Deteriorated insulation. Insulation will deterior- 
ate with normal usage. A factor greatly affecting de- 
terioration is sea water. Salt water will cause salt 
deposits to form on the terminal and wiring. This in 
turn causes a mild short circuit resulting in heating 
and deterioration of the insulation. Such deposits are 
often responsible for discharged storage batteries. The 
terminals and wiring should be wiped frequently with 
a dry cloth to minimize this trouble. 

Oil, grease, and water will also cause insulation to 
deteriorate. The wiring must be kept clean and dry at 
all times. A coat of varnish applied to the wiring will 
help preserve the insulation. 

(c) Failure to strip armored cable properly. If the armor 
on electrical cables is not stripped back sufficiently 
from the end of the cable, it is possible that it will 
come in contact with the terminal lugs, and thereby 
cause a short circuit. When preparing connections for 
armored cable, the armor should always be stripped 
for a distance of six inches from the end, and the loose 
ends of the armor taped to prevent fraying of the cable. 

Short circuits can be prevented by proper care and 
periodic inspection of the wiring. When inspecting the 
wiring for wear and potential shorts, particular atten- 
tion should be paid to bends, clips, terminals, and 
places where the wire is unprotected and subjected to 
oil, water, and scuffing. 

2. Repair. Repair to the wires should be made in 
the same manner as for burned insulation. The wire 
should be inspected at the point of insulation failure 
to make certain that the metal of the wire has not been 
cut or burned away, which is quite often the case. A 
weak point or section in the wire will result in in- 
creased resistance and heating. 


9E1. General. Remote control speed adjustment 
is accomplished electrically by the following systems: 

1. A.C. selsyn motor. 

2. D.C. selsyn motor. 

3. A.C, D.C. split field motor. 

The prime function of these devices is to enable 
switchboard operators to match generated voltages 
and to adjust the power distribution. This is accom- 
plished by changing the speed adjustment on the 




to eeveese direction of rotation Of imoicgtor 
motor, eeveese its rotor leads Ri a rs 

Figure 9-16. Diagrammatic sketch of connections for self- 
synchronous transmitters and indicators. 

9E2. A.C. selsyn motor. The a.c. sclsyn motor is 
essentially a transformer with a three-leg rotating 
secondary winding. 

The a.c. selsyn units are operated only on 115-volt 
60-cyclc, single-phase, alternating current. The sys- 
tems are composed of a transmitter and one or more 
repeaters. The construction of the repeaters is identi- 
cal to that of the transmitters with the exception that 
a dampening device is built into the repeaters. 

In Figure 9-17, it should be noted that the only 
power used is that required to energize the stationary 

US V 60 C YC LE A C 1 




~r7] f~Ri rTI «71 

Ml LimU yML 

s, 3 | s 2 s, [ P] s 2 s, 1 H s 2 

I 1 i 1 




Figure 9-77. Wiring diagram, selsyn remote control, a.c. 

coils. These coils arc wired in a parallel circuit with 
all terminals marked Si connected to one power lead, 
and all terminals marked S2 connected to the other 
lead. The rotor connections are made by connecting 
all Ri terminals together, all R 2 terminals together, 
and all R 3 terminals together. 

a. possible trouble: 
no response to changes of transmitter 

Digitized by 

Go gle 

1. Causes and prevention. Failure of the remote con- 
trol device is caused by one or more of the following : 

(a) Not energized. 

(b) Loose connections. 

(c) Dirty brushes. 

(d) Defective bearings, 
(c) Defective coils. 

(a) Not energized. This is due to failure to turn on 
the energizing power. The fuses and circuit breakers 
should be checked. 

(b) Loose connections. Loose connections will cause 
the units to operate improperly. Each unit has five 
connections. Any one of the five, if loose, will cause 
erratic operation. 

(c) Dirty brushes. Dirty brushes or slip rings will 
cause poor contact with the rotor. The result will be 
the same as that caused by a loose connection. 

(d) Defective bearings. Bearings worn or damaged in 
any way will cause the rotor to bind, and possibly 
lock. This is always accompanied by a humming 
sound. Damaged and worn bearings must be replaced. 
New bearings should first be cleaned of the vaseline in 
which they are packed, and then lubricated with a 
light oil before installing. 

(e) Defective coils. Burned-out coils arc often encoun- 
tered. The coils should be inspected after other pos- 
sible troubles have been checked for. 

Such troubles as listed above can usually be pre- 
vented by using proper care. Terminal connections 
should be checked to insure that they arc tight. The 
cover should be removed and the slip rings and 
brushes inspected. If the brushes are more than fifty 
percent worn, they should be replaced. 

2. Repair. When disassembling a unit, the brushes 
and brush bases should be removed first. The bolts are 
then removed and the unit pulled apart, exposing the 
rotor and field coils. Care should be taken that the 
shims are kept intact and replaced in the same posi- 
tion. The proper end-play clearance is .010 to .015 
inches. If the brushes and commutator are dirty, they 
should first be wiped with a dry cloth, and then fur- 
ther cleaned with 6/0 sandpaper if necessary. When 




reassembling, a light oil should be used to lubricate 
the bearings. 

9E3. D.C. selsyn motor. The principle of opera- 
tion of the d.c. selsyn is entirely different from that 
employed in the a.c. selsyn. Figure 9-18 is a schematic 
diagram of the operating principles of the d.c. selsyn. 
The receiver is essentially a set of three stationary 
electromagnetic windings on an iron ring, supplied 
with varying voltages from a circular resistance unit 
of the transmitter, which has three taps. Power is 
supplied the resistance unit through a contact arm 
which can be rotated. Rotating within the ring of the 
receiver is a magnetized rotor. The rotor may be 
cither a permanent magnet or an electromagnet, as is 
shown in Figure 9-18. 

The units have five connections. Power is supplied 
the terminals marked Ri and R 2 . Ri and R 2 of the re- 
ceiver are connected in parallel to Ri and R 2 of the 



Figure 9-18. Schematic connection diagram 
of d.c. selsyn system. 

a. possible trouble: 
selsyn fails to operate 

1. Causes and prevention. Failure of the selsyn to 
operate may be caused by: 

(a) Binding. 

(b) Open circuits. 

(c) Dirty contacts. 

(a) Binding. If the selsyn receiver fails to operate 
when the transmitter is turned, a check should be 
made for mechanical binding of the parts. Particular 
attention should be given the bearings. Dirt or other 
foreign matter in the bearings will prevent the rotor 
from moving, making the unit inoperative. 

(b) Open circuits. The electrical connections must be 
checked for open or incorrect circuits. An improper 
circuit will prevent the unit from operating. Defec- 

tive windings can usually be detected by resistance 

(c) Dirty contacts. Dirty contacts will cause voltage 
loss to the resistance unit, thereby causing only a 
weak response, or possibly none, to a change in the 
rotatable contact arm. 

Troubles can be averted with only a minimum of 
maintenance. Standard receivers are equipped with 
ball bearings and do not require much lubrication. 
Brushes should be removed periodically and the collec- 
tor rings inspected for dark spots or pits. Collector 
rings should always be kept smooth and clean. The 
brushes should slide freely, and the spring force should 
be just enough to insure good contact on the rings. 

The transmitters should receive the normal care 
given plate type rheostats. The contacts must be kept 

2. Repair. Should trouble occur other than loose 
connections and dirty brushes and collector rings, it is 
most advisable to replace the unit as a whole. 

9E4. A.C, D.C. split field motor. The split field 
motor is used extensively on the Woodward SI gover- 
nors for remote control. The power unit is a split field 
series wound motor. It is wired as shown in Figure 9-19. 



110-115 V. 


Figure 9-19. 


Wiring diagram. 

a, possible trouble: 
motor fails to operate 

Digitized by 

Go gle 


1. Causes and prevention. Failure of the motor to 
operate may result from: 

(a) Loose connections. 

(b) Dirty brushes and commutator. 

(c) Defective coils. 

(a) Loose connections. Loose connections will prevent 
the motor from operating properly. All connections 

Origiral frcrn 


uiust be eh^kfcd pcndaiolly to insure thar-rhcy 

(h) brtuhti and iommutalor. CHL grease, ana 

dirt .collect on the commutator and brushes, thereby 
QMmog loss o£ power or complete failure of the motor 

(c) Defective foils : Open or J\< *n arcm fsjii die rotor 


washer. This wear jjf Unpfeve^^ble, and only bv fre- 
quent inspection can rhi* tfftuhie br prevented. 

2. . Rtpttit... Motor f a j lures -ire the same, a* f*>r any 

mu&r. be kept right 

clean. The two-way switch on *he.*vmch&fwd must 
aJso be checked periodically to msorc {Proper contact 
If the contacts are dirty or pitted, they should be 
cleaned with sandpaper or a point hie 

- — ■ — - — — 


A- , 

' - \ ' 

~ — — fis»r* 9-20, AC, D.C *plH flM mote. 

A itfp coupling j& provided «n the drift from the 
motor to xhc *pced adiu&un* gc:u trams "fftti allows 2. J?i#*rr. Slippage can be- corrected- either .by plao 

mg and the slip 
new fibre washer-; In 
do both A check 

n as long as u does not slip . when being should be made id insure that the knob oti rhc govcr- 

e motor. ; nor can be turned readily. On sonic governor rheilip 

1 C^i^i-'^rei^H&t. Slrppa^e js cause*] Hv wear awpliug screw and phc slip \coup)i(^ out arc 'pinned 

.rA..iiu,.^u. ; .,„^ ir ; ,v- .....t. v i . . T k.. ' ... LJ 

any attenti&j 
driven by the motor 

Digitizes by 


components of the engine frame are variously Gw»W Thiv is die hou*i< . 

referred t« « th**vlmdcr block, cranks*. bedpLut. illustrates rhe cttflfcustfar <Ua>-»8. The 

oil pan, end pbtes etc tn some engines a PF* r portion of t be, housing, ferfu'dfr may be termed 

. L .1 .1. til. _ j' . _1 j sirnnlv crankcast. rnav be bolted to or .made ...intcfffal'' • 

gyp p 

•/e«\ 5(>me i tners are 
A phages, and the 

tv^e do not 

Many -.blocks huved 

"are provided with integral cool- of J crartkease explosion, thereby preventing 'damage 

* cylinder blinks for engines of to crankcase. in other engines, rhe hand-hole 

n ccner;d)v have cooling passage <* vcr f^ to m *>' he fitted with j spring loaded ex- 

,cd„Hcd InbcoH r, lW ^m twa- : ^™ vent. 

. *trc&e cvcie engines h.m -m passages m the block Bsc! flan The function <ti Mmip\i 

the .cylinder block of j forge engine. Ako-558, is the main bearings of the engine. The crankcasc is 

ill unrated hv Figure lcv-1. to some • ^.ncs. f here is 'hnlted to rhe bedplate and the oil pan is bolted to the 

i^^P li ^iiai it . . . ; ^m-i Si ; Hi ft li ■ 


$ ..ft"''' 


hauls when they arc suspected of being loose, and at 
such times as specified in the progressive maintenance 
schedule for the engine. These bolts must be tight- 
ened evenly. 

(b) Overheating. Cracks may develop in the block as 
a result of high local temperatures, or sudden cooling 
of a hot spot. High local temperatures usually develop 
through inadequate cooling. This may be caused by 
clogging of the cooling passages, or operation without 
properly functioning cooling water pumps or water 
coolers. It may also be due to maintaining cooling 
water temperatures too high (above 180° F), so that 
steam pockets are formed in the cooling jackets. 

If the block has become overheated for any reason, 
cold water should never be circulated suddenly through 
the passages, for this will cause rapid and uneven 
contraction (see a. Possible trouble: Excessive scale for- 
mat ion in passages y page 156). 

(c) Inoperative vibration isolators. Vibration isolators 
are occasionally installed on generating sets to absorb 
the forces of shock and vibration. If they become dam- 
aged, the forces due to shock, misalignment, vibra- 
tion, or uneven support may become so severe that the 
base, and in extreme cases the block, will be damaged. 
It should be remembered that vibration isolators are 
not used on many engines. In cases where only mount- 
ing bolts are used, it is of prime importance that all 
these bolts be tightened evenly and sufficiently. For 
possible derangements of the vibration isolators, see 
pages 197-198. 

(d) Internal failures. Serious derangements of the 
internal machinery of the engine may cause parts to be 
thrown against or through the engine frame. In some 
instances, connecting rod bolts have failed and al- 
lowed one end of the connecting rod to break loose and 
fly through the side of the crankcase. Pieces of failed 
gears may also break through the housing. Such 
derangements are extremely serious and are hazardous 
to nearby personnel. Resultant damage to other parts 
of the engine is usually so severe that the damage to 
the frame will appear to be only incidental. The dan- 
ger of casualties of this nature may be greatly reduced 
by operating the engine at all times within the range 
of speed and load authorized by the Bureau of Ships. 
Overspeed protection devices, if installed, must be 
maintained in operating condition. Likewise, the 
importance of maintaining other engine parts, such 
as bearings and gears, in proper condition of adjust- 
ment cannot be overemphasized. 

(e) Misalignment. If the engine driving shaft is not 
properly aligned with the shaft of the driven member 
(generator, propeller shaft, reduction gear, etc.), 

Digitized by G(X '2^ 1 

vibration or excessive strains will be induced and 
cracking of the frame can result. 

Misalignment between parts of the engine frame can 
introduce eccentricities that may cause undue stresses 
to be set up in some portion of the frame. It is usually 
rather difficult to misalign main parts as most of the 
bolts are closely fitted to the holes in the adjoining 
piece; also dowels are frequently provided. However, 
flanging surfaces should be thoroughly cleaned, par- 
ticularly when pieces of the old gasket are adhering to 
them. Before bolting them together, any burrs or 
other protrusions should be removed from the sur- 
faces. All bolts should be evenly tightened. 

2. Repair. The successful permanent repair aboard 
ship of cracked cast iron frames is not usually possible. 
Welding is the most successful means of repairing such 
cracks, but to avoid setting up stresses in the frame in 
the vicinity of the weld, it is necessary to pre-heat the 
structure and to cool it slowly after welding. Conse- 
quently, in cases where welding is necessary, the en- 
gine must be taken to a repair base or navy yard to 
effect these repairs. However, in an emergency, when 
it is necessary to continue operation of the engine and 
operation is not possible without some measure of 
repair to the crack, a temporary so-called cold weld 
method is effective in stopping leaks. This method can- 
not be used successfully even for temporary repairs 
where the cracked part is subjected to very great 
mechanical or thermal stresses. None of these cold 
weld processes involve welding in any form and such 
repairs are entirely mechanical. For naval use, such 
processes shall be considered only as a temporary 
emergency means of repair, and must not be used for 
permanent repair where welding is available or re- 
placement of parts can be made. 

The two most widely used of these processes are the 
Harmon Sav-A-Weld process and the Metalock 
process. The Harmon Sav-A-Weld process is shown 
in Figure 10-5. In this process, overlapping holes are 
drilled three-quarters of the way through the material 
to be repaired. The holes are drilled in rows that are 
transverse to the crack and spaced approximately 
13^2 inches apart along the length of the repair. These 
holes are for receiving the Harmon locks, which are 
scalloped strips of Invar or nickel steel approximately 
Jfg inch thick and of various widths and lengths. 
These strips are stamped out in a shape similar to a 
series of overlapping cup-shaped disks. After inserting 
each lock, convex side up, it is peened flat before the 
next lock is added on top of it. After a sufficient num- 
ber of locks have been added to fill the holes to the 
top, and all of the locks have been peened into place, 

Original from 


the portions of the crack between the locks are drilled 
and threaded for closely spaced studs. Studs are then 
screwed into place and peened over. To insure pres- 
sure tightness, a sealing compound may be used during 
the placing of the locks and studs. 

Figure 10-5. Harmon Sav- A- Weld method for re pairing cracks. 

The Mctalock process is shown in Figure 10-6. In 
this process, rows of equally spaced holes arc drilled 
along the crack as in the Harmon process. The two 
processes are exactly the same except that in the 
Metalock process, it is necessary to gouge out the thin 
walls between the holes transverse to the crack so that 
the key, which is a bar of Invar, will fit. It will be 
noted that this bar of Invar differs from the Harmon 
key in that only one bar is required. After insertion, 
the Metalock bar is peened into place causing the top 
of the lock to expand and fill the slot. As in the Har- 
mon process, closely spaced studs are installed in the 
holes along the crack, and a sealing compound is also 
generally used. 

The keys and studs for both processes come in 
various sizes and lengths. The larger sizes are used for 
larger cracks. 

Cracks in fabricated steel or cast steel frames may 
be repaired successfully by welding aboard ship if a 
qualified welder is aboard. Prior to welding, the orig- 
inal alignment of the parts must be determined and 
measurements taken between certain fixed points. Dial 
gages should be at hand for determining these 
measurements with the required accuracy. The extent 
of the crack should be determined by the magnetic 

powder method. Consequently, it is more desirable to 
wait until facilities for this determination arc avail- 
able. However, in an emergency, a generous estimate 
of the extent of the crack should be made to avoid 
failing to weld the crack in its entirety. The portion 
of the plate containing the crack should be removed by 
grinding and chipping so as to form a groove extend- 
ing at least J^-inch beyond the end of the crack in any 
direction. In order to effect a permanent repair, weld- 
ing should be done from both sides of the crack. When 
this is impossible, a backing strip should be fitted to 
the inside of the crack to permit a 10C percent weld at 
the root. The weld should be applied in wandering 
sequence (see Figure 10-9). It is obvious that dimen- 
sional stability must be maintained throughout the 
welding process. This will be accomplished by peen- 
ing while the welding metal is being applied. Any 
tendency to warp while cooling, indicated by the dial 
gages, should be corrected by peening. After welding 
has been completed, the outside surface of the weld 
should be ground flush with the adjoining surfaces. 
It is essential that the final distortion of the frame be 
kept to a minimum; consequently, it is preferable that 
these repairs be made by navy yards, tenders, or bases. 




Digitized by 



Figure 1 0-6. Metalock process for repairing cracks. 

d. possible trouble: 
clogged oil passages 

Many cylinder blocks have drilled oil passages 
which conduct oil from the main lube oil header to 

Qrigiral from 

^ - t>Jaf , k d' : ';.x/'.h ;V W d' 

particks will be dropped into die cr an kcuse. These 

parts rcQ;umf^ parades will be <; 

Burning" or mpim of a bearing or other part, which ttuy clog 
may io*iiC4i£ itjsufhdcnt lubrication, may be a symp- cleaned catt/uiJ% di 

the passages. The engine must be 

— — 


down the . engine parrs, dirty *m pas&ao&v 

eating oils, the 9000 series NUvy iuhe oils, arc indis- ^ A, * ,At lW( - scr 


(a) Excess accumulation of oil in the air box. The air 
box is usually considered to be that portion of the in- 
take air passage within the cylinder block. Accumu- 
lation of oil in this space accelerates the formation of 
deposits therein. The remedies are discussed in Chap- 
ter 2, pages 23-24. 

(b) Foreign matter in the air intake system. Careless- 
ness on the part of personnel may result in objects such 
as rags, tools, etc., being left in the intake manifold or 
air box when the system is closed. A systematic inspec- 
tion for foreign articles left inadvertently in the en- 
gine must be made after working upon it. Such articles 
can clog the ports in a cylinder and prevent combus- 
tion. If the article is small enough, it may be drawn 
into the cylinder and ruin the cylinder liner, piston, 
head, etc. If no air intake strainer is installed, care 
must be taken not to allow small articles to be drawn 
into the system through the air inlet. 

2. Repair. Air passages can be cleaned by use of a 
wire brush in most cases. Solvent may be used for the 
final cleaning operation, but it must be made certain 
that all the solution is drained from the air box before 
commencing inspection. In many engines it is neces- 
sary only to remove an inspection plate to gain access 
to a passage. Dislodged particles must not be allowed 
to drop into the cylinder or crankcase. Rags should be 
placed in position to catch all of the cleanings. 

e. possible trouble: 
crankcase explosion 

The extent of the damage caused by a crankcase ex- 
plosion is unpredictable, but it frequently includes 
bent connecting rods, sprung or broken crankshaft, 
and broken liners and pistons. Occasionally engine 
room fires of a serious nature occur after an explosion. 

1. Causes and prevention. It is difficult to determine 
the cause of crankcase explosions because of the exten- 
sive damage resulting from them. Usually they occur 
in engines in bad general mechanical condition, where 
seizure of the pistons and other metal-to-metal contact 
are likely to occur. Some of the causative factors 
in crankcase explosions are: 

(a) Crankshaft bearing failures. 

(b) Overheating or dilution of lube oil. 

(c) Poor condition of cylinder liners or piston 


(d) Cracked piston. 

(e) Seized piston. 

(a) Crankshaft bearing failures. If an engine is oper- 
ated with crankshaft bearings in poor condition for 
any length of time, it is possible that sparks may be 

Digitized:, CjOuQIC 

created if the bearing disintegrates and causes the 
journal to make contact with the connecting rod. Also, 
the heat liberated by the faulty bearing will aid in the 
vaporization of the lube oil. Sparks or open flame in 
the crankcase must not be allowed, as they may, under 
the proper conditions, set off a crankcase explosion. 
When it is noted that a bearing is becoming excessively 
worn or has failed completely, the engine must be 
secured at the earliest possible moment. Continued 
operation may cause a crankcase explosion, and may 
also cause mechanical damage to the connecting rod, 
crankshaft, etc. The operator should be alert to recog- 
nize symptoms of bearing trouble as quickly as pos- 
sible (see Chapter 15). Improper thrust bearing ad- 
justment or worn thrust bearings will permit crank 
cheeks to strike against a bearing shell, causing 
sparks that will ignite explosive fumes in the crank- 

(b) Overheating or dilution of lube oil. Explosive vapors 
are almost always present in the crankcase when the 
engine is running. These vapors may be ignited by 
sparks or open flame, causing a crankcase explosion. 
The formation of vapor from lubricating oil is greatly 
accelerated by a rise in the temperature of the lube oil 
due to a hot bearing, the seizing of a piston in the 
cylinder, etc. 

Overheating of the lubricating oil has other serious 
effects. The viscosity of the lube oil will be greatly 
reduced, and the tendency to form gum increased. The 
operator should therefore maintain lube oil tempera- 
tures at the value specified in the instruction manual. 
If he is unable to do so, he must determine the cause of 
the trouble and eliminate it. 

Dilution of the lubricating oil with diesel fuel will 
increase the tendency toward vapor formation in the 
crankcase. This is due to the fact that diesel fuel has a 
lower flash point than lubricating oil. In approxi- 
mate terms, diesel fuel will give off vapor in sufficient 
quantities to be ignited when it is heated to about 
150° F. On the other hand, lube oil must be heated to 
about 250° F before it reaches the flash point. 

It should be remembered that dilution alone cannot 
cause crankcase explosion. It may, however, contrib- 
ute to making it possible. Dilution is generally a re- 
sult of poor condition of the engine. It may be recog- 
nized by testing a sample of the crankcase oil with 
a Vis -Gage. 

Dilution has other harmful effects. It reduces lube 
oil viscosity, and may reduce it to a dangerous point. 

(c) Poor condition of cylinder liners or piston rings. If 
the cylinder liners or the piston rings are in poor con- 
dition, they will permit blow-by. That is., the gases 

Qrigiral from 

biowd itico the crankcase.' "Tlv^-Wel-c. of the hoi gara, aankcatt explosions. The symptoms of a cracked 

- - ---- •• - • '«*•••• - - ^msed, aid the eogfae 

m such condition is 

is co vaporise die iuhnc^tmg toi If arty flame is piston should be quickly r 
allowed to pass the nngs, iuusy ifcnuc the vapors, and ; should never be opemed 

cause a erankcase explosion- Only- in cases ^'extreme "evi 

r ccr condition for 

lowed e*acdy* and the cn^mc should not be opcr- dmokcaie wsplosions, The seizin* of pistons can be 
ated for any length of nrae with badly worn piston prevented (see Chapter 1% page 240). 
-nags or scored -"cylinder. .liners..-' 

i j i..: ..f J.i ^*Ja1^~ t JL- tt.r^w. .rcL:^ i • 

has resulted from Tbi$ trouble becomes appjrcnc through .t>^a,tion. 
the cto mpfcvtm damage due ci> nmaligrtmenc of the sub-fe*e Unless careful tospections are made, 

TCuraCcJocation of thfcirobhlc mav ni»r V nwrd nnrti th^Mtfin^ itmwhm. 

bolt holes and ab$alute rigidity of the sub-base is tew 
essentia!, mi 

arc c 


1QC1. General. Mountings 

r:i'' rafts' 


mi oi mam 

Although flexibic.'nrKiuncifngs xrc 
every type, of generator set, rhey arc dcsirAbfc ? 

gc«craung. $m mounted neac (he side of the hull m ^ fit 

order to reduce hull vibrations and make nearby spaces . : . 

Figwrm 1Q-11> FundamentoU of Yit»athn hofott*. 


There ire two general classes of fiti ible mountings, 
although both may he incorporated in Pnr device. 
They are rfac vihrauos LsoUrof and the shock uhsorbcr . 
The function of" the vibration Isolator is to absorb the 
forces of relatively high- frequency small -ampbr.ulc 

ro correspond to x: ■high-frc- 
vjuency Vibration, rhc wei^hc will tend fo reman ac 
rest while the sprang is elongated and compressed. 

Thus, t 

. by the Hexing oi vhc spring; 

vibration*. The inherent unbalance Of -the engine it- 
self gives --rise' to ihese vubranooa, TW action vf --*n 

steel plates 


crates one rvpeuj. which the rubber block is beaded to mechaaioiJ energy to be changed into beat of friction , 
«wi nbn^ whtcb is disstpatevJ in- the air surrounding the unuY.'-' 

beyond Us capacity and the weight- vytH receive a jolt site direction on the plunger will likewise rend lacom- 
which will move it The spring miiy be perm^endr press and expand chc ring springs, In a later design, 

deformed,, and may even break if the shock is- sui 

suffi- the. pi anger us so arranged chat shock loads trans verse- 
sola- to the aits. of the pkwmt are bkrwise absorbed. 

>s illustrated by Figure 10-14 

sion of vibfatum to the structfjue ol" the ^ 

plunder & is \tifccnr up. The plunger pushes down on . t_ , , i_ • i . \ . 

thc o<iWru)^ spfi'if C whns^ bevel ~d 1 face rs opposite .laxor-shock absorber; wuts, sucn as that shown in 

. «.va. ' e M 

C m». 


^-.-Y\Y ' . • ' • * • . 

;'y-*:' y Y'. 




No adjustment of the shock absorber unit should 
be attempted, as it is set at the factory. 

If it is noted that too much vibration is being trans- 
mitted to the substructure, the clearance at point 
C (Figure 10-14) is probably improper. 

If the engine sways or lurches too much, it is likely 
that there is not sufficient tension on the coil springs. 
This can be corrected by screwing down on the 
leveling bolts. 

When making adjustments, the clearance C should 
be about the same for each isolator unit. The clear- 
ance limits are usually stated in the engine instruction 

(b) Failure of elastic absorber. The elastic absorber 
may be a set of metal coil springs, a cushion of rubber, 
some semi-fluid plastic material, or a combination of 
these. Breakage of the springs, tearing or unbonding 
of the rubber, or loss of the plastic material will render 
the vibration isolator inoperative. 

The cause of the failure of springs may be corrosion. 

Every effort should be made to protect the springs 
from the action and corrosive effect of salt water. 

The failure of rubber is generally due to the action 
of oil, grease, or other deteriorating agents. Precau- 
tions should be taken to protect rubber isolators from 
such agents. 

Loss of plastic material usually occurs when a vessel 
is operating in a hot climate. In most cases, the tarry 
material flows out where it can be seen, and the 
dampening action of the isolators disappears. In an 
effort to overcome this difficulty, the manufacturer has 
attached a fitting to the isolator through which addi- 
tional plastic material may be introduced. However, 
it is preferable to try to replace isolators of this type 
with the non-plastic-filled type. 

2. Repair. The cause of maloperation of the isolator 
must be determined and corrected by the adjustment, 
or replacement, of any failed parts. Where failure has 
been severe, it may be necessary to replace the entire 

Digitized by GOOSES 



... .: ' •.. .\a<. f • A'. >™. (foiA' * . ■ SvSr.&ftaB 

...... . 

» *• ■ . . . - • «<• • • 

; . . > \ . > 

m tefr'J 



|»1 1 3«v»2 

aa-a.A: .v. a: et ' : 


Figure 7 7-2. Cylinder head requiring no gasket. 








Figure 1 7-3. Types of cylinder liners. 




Original from 

university of, Michigan 


. * . ! 


other foreign matter fhc seating .^irf:c£s. S»imter!>\ ; ' v' 

j^lcs, bum, or improper ifillcu oo the scad ng surfaces ^ 
mav prevent proper positioning. Figure 1JW illm Fi#wp 1f~7 t 

(*) introduction .of ftuhn 
drawn into the engine 'Wit 
oil and act as an effective 

Larger j 




ated in a dirty condition \ 

When rc^scniblh^ an engine, a fx^iuve check 
should be made of each cylinder prior to replad^ 1 
i he cylinder head or heads ti' rhts is nor done, meta! j 
chips, nuts, screwy rook/ or dirt nuy be let t in the jj 
cylinder to cause hrc;-k.i^ 
headL $ fche .article ii srnaM', 




PISTON v \, 

yip t" ™*£ s $' : $ * 

|| rhc .increased remperanire. Furthermore, a badly available, and then only with en^ino for vvhrch the 

The method .-'of cvhoder wall (librae 
determined *V'a particuUc inguic 

rrrtA»r\ rh is >.\t vm) vvAk^x&w zrP f \e»*v 

tendency toward air bo* explosion*. This ,vudnion 
can be averted by careful arcane ion to the cleaning of 
these drains (see Chapter .11, pige 15). 

rings or TapiJ'wwof ptstpn rings may indicate exces- 
S! vc.. cylinder tvear 

The anvsc conducive test as ro whether or not. a finer 
is worn is made by ufc dig meAsniicmciiWof thc'ltacr 
with inside micrometer calipers. The type* of wear 


evident to iht o^i.noi . Figure I i - 1 > indicat res rhccyJ'mdtr w/JI, *nj the achct ^ndtpavcdx ; -:||^^^ 
methods of fn^sii^ncnf. ^ ^ ^ per* 41* then* rocked up .thJ Ja\<^^^|^^^^^^[ 


AttcnciOT>Ko,rid *lso be gi^n ;u> i of Oil, ir should !>c made certain that the 

cbs«ty and type, deviated bv Navy Numher, is as Phi), No. S4l05~3$9692. t nm>i be 

specified far the engine When salvage facilities arc a v. 

(0 'Drtfy ensim, The ec^ine iiitjit not be operated ux to tec) aim worn ' 
a dirty cc-nditiorf. The air hbx; erankcase, and mam- 
fold should be elcao and nWiiHaliied in that 

condition to j. void cylinder wear or scoring.. Acccirtion then madfmjed. -th ; perfect .soundness. The. finer is 

to the air doner, ojf 'filers, and oil ce.ritrifuge are the chroxrrmrn pij.tcd nnril it is sirghrly smaller Ln diam- 

»$ mm 

• • t 
1 1 ' 

| - , 

rare dft J 

to* ' • ' 

1 I MIK 


**** • • 



• .. • ' •■ ■ I - .: ^ ■ 

is. in which the shape of the head pro- -iostifilct! in the hod.. TIk of Jpysed piston cogint is-. 

exhaust va!vs:f. ; gutifcs, aiUt scats, 

Mill ■ • . 





■ " *.'•' '. ' . • , • ' 


MAKE-UP L|NE==v :£ /%^ 

, , XV TtlBlklA 



^1— , ■ . r~ , — 


L ■ : 1 

FiWll-iO. S*h»f> to ttuhrga* in cooling »„t«r. 

/Vv/H- • f/,V A .v.v v.* 

. , ... : ,, . . . ... .... . ■ 

injector, and screwiag an i«lijtt*r for the ship's service 
air hose mm-th^r hole. A- bubbling sound when air is 


If removed from . the engine', the cylinder head may 

However, visual or "magnetic powder inspection of the 
questionable head h die most reliable test. The pre* 
encc of water in a cornier after a period m shutdown 
or in the lubricating ojj. may ind ica te a cracked cyj i n- 
der head The presence of gases of combustion iu t he 
cooling water liiay also indicate a cracked cylinder 
head. Tfos triay be wm'aincd by-jnafc-ing the Cooling 
system pressure t*ght and tapping a test line into the 

arrangement of this test ^r-iip. 

The test hoe is submerged in a container of water. 
As the cooling srstetn is under pressure, and the gases 
of combuswoa will pass into the cooling water ami 
increase "i*s pressure, a flow of gas from the end of the 
test hose: -win be apparent below the surface of the 
container, it should be remembered, however, that 
gas i<uh* cqoftng w; U er may ate> indicate a'cracked 
line, , leukv gasket; or air being drawn an throudi a 



will leak from even the most minute cracks. Large 
cracks may usually be located by cleaning the head 
thoroughly and examining it carefully. 

Figure 11-21 shows a cracked cylinder head. Cracks 
occur most frequently on "bridges" or narrow metal 
sections between valve and injector holes in the head. 
These areas should be scrupulously examined. 

Cast iron heads may be subjected to magnetic pow- 
der inspection when small cracks are suspected but are 
not visually apparent. 

1. Causes and prevention. Cracked heads may be caused 

(a) Addition of cold water to hot engine. 

(b) Restricted cooling passages. 

(c) Improper tightening of studs. 

(d) Obstruction in combustion chamber. 

(a) Addition of cold water to hot engine. When an engine 
has been allowed to overheat, it should never be 
cooled by quickly pouring cold water into the engine 
as this may cause cracking due to thermal stress. If it 
is necessary to add water, the engine should be al- 
lowed to cool before pouring in the water. In an 
emergency, if it is necessary to continue operations, 
the cold water should be added in small increments, 
while the engine is operating, at intervals sufficiently long 
to insure thorough mixing of the cold water with the 

(b) Restricted cooling passages. When cooling passages 
become clogged or dirty, there is likely to be insuffi- 
cient heat transfer, with consequent overheating of 
the metal. This can result in cracking due to over- 
expansion. Cooling passages should be kept clean by 
following the cleaning procedure set forth in the 
Bureau of Ships Manual, Chapter 41, Section II, Part 10. 

(c) Improper tightening of studs. Cylinder head studs 
must be drawn down evenly, in the proper order, and 
in proper increments. If this is not done, some of the 
studs will be loaded more severely than others and the 
head may deflect in the region of the loose studs. The 
cylinder head gasket will be pinched in the region of 
the tight studs, and blow-by may occur near the loose 
studs. See Figure 11-37 for the correct procedure in 
tightening cylinder head studs. 

(d) Obstruction in combustion chamber. In many cases 
cylinder heads have become damaged through the 
introduction of foreign bodies into the combustion 
space. The minute clearances necessitated by the high 
compression ratios of diesel engines will not accom- 
modate any large metal particles or appreciable quan- 
tities of water. On numerous occasions, intake or 
exhaust valves have broken loose and dropped into the 

Digitized by CjOOQIC 5 

combustion chamber and caused extensive damage to 
the piston and head. This trouble can be prevented 
only by thorough maintenance of valve gear. (See 
Chapter 12 for valve maintenance hints.) 

In certain instances, injector tips have become 
clogged, causing breakage of the tip and consequent 
damage to the head and piston by the broken injector 
particles. (See Chapter 4 for proper maintenance of 
fuel injector equipment.) 

Observance of precautions in starting the engine 
will prevent breakage of piston or heads by water in 
the combustion space. 

Obviously, great care should be exercised to prevent 
the entrance of any metal objects, such as tools, nuts, 
bolts, pieces of wire, and similar objects, into the com- 
bustion space during overhaul of the engine. Injector 
holes in the head should always be covered when 
injectors are removed. 

2. Repair. There is no wholly successful method for 
repair of cracked cylinder heads aboard ship. Various 
cold metal welding processes have been attempted, 
but none are approved by the Bureau of Ships for this 
type of repair. 

Welding of heads can be accomplished by careful 
regulation of pre-welding and posr-welding tempera- 
tures, but the equipment necessary for such extensive 
repairs is not generally available. Moreover, only 
highly skilled personnel are qualified to make repairs 
of this nature. 

It should be remembered that attempts to weld 
heads must be carried out only with proper equip- 
ment, such as thermostatically controlled furnaces^ 
and by highly skilled personnel. Otherwise, warpagc* 
or cracking more serious than the original derange- 
ment, will result. 

b. possible trouble: 
burned or corroded cylinder head 

This trouble generally becomes apparent by a hiss- 
ing or sizzling sound from the region of the head. 
Gases of combustion may be seen leaking from be- 
tween the head and the cylinder block. 

In severe cases of corrosion, there may be intro- 
duction of water into the combustion space. Less 
severe cases will be evidenced by formation of oxide 
on the surface, and pitting of the surface. 

Figure 11-22 illustrates a cylinder head burned bv 
operation with a leaky gasket. 

1. Causes and prevention. Burned or corroded cylin- 
der heads arc due mainly to: 




, . m ^ ^ relieve mc cyimucr bow auer wci^ng wjn insiiqe* ; 

^WBftbfe* di^tbrciVi at)^! ? possibly, further crackm£. . 

^ l '^ Hcnm £ °* cvl?iU ' t:r ucaJ scuds can nuiucc 

' of* he head (Sec >) improper rtghecning of hoitMow)) 

Z. Hjpa/r. Kzp&it qt &\st&nx&.ty) <n'<jcr tieads is not 
practicable; They should be replaced .k the caHiesr 

flftgti Cylinder heatl showing effat of hakirig go$k*t, 


ptopcr assembly 

of combustion chamber ports cart pohshod wuh ctocus cloth. GencraOv sptafctRe, cbc 


v.- . ■ •• 

I studs in posit KM) in, the cvltndcr 

Is threaded at either end, and 
imuiiv made »t alloy tad. ^ Genera] tv, the threads 

, .... , . ; .. . .. . 







[ . 

Mfew$w ' iiil - 


Most stud brc;ifcase occurs as shown m Bguire 11*43. Bdfli 


Mi- ^ 

occur s a result of; 

(a) improper tightening of stud nuts. 

(V) improper stud installation. 

mmm . 

■ ■X 


. .. y 

to cause fail 

The torque specifications for a particular engine 
should nor be exceeded 

If all Mvds are bjoii; tighieneo* equally, the tighter 
studs will take the bulk of the iri,id As the designer of 
the etigine worked out stint d) mentions on iht hms of 
all of the *tuds sharing the ]o*A y h is to be expected 
that everscres5ing and failure of. studs will occur if 
only a few are made to carry the fiilj load, Figure 
11-27 shows in exaggerated form the condition 
exists when a few studs arc tighter than others. If the 
head is sufficiently fkfcibk, the loose studs may be 
subjected to shock load when that port too of the head 
is pushed oucward hv the forces of .cptubustioa. it is 
obvious that this is a iVighlr undesfrabk condition. 

acss In many instances, certain studs are quite in ac- 
cessible and for that reason they are neglected when 
studs are periodical!* checked for tightness. Con*. 

inconvenience of proper t^hie^i rig must «/»/ be 
allowed to interfere with iTuuHcnanc*: of required 
equal tightness ir should be remembered that if wiU ■ 
bt fax tnott incmvntmtt to : n»i*>vt a btbktn sink 

When installing stud nuts, the rbrcads of the studs 
'mi the mu should be carefully cleaned by vy/ce brush- 
Wg and application of a solvent. Th|> will minimize 

tonque wrench reading will be necessary to reach re- 
quired tension when the threads ate dirty than when 
they arc clean and well oiled 

vb) Improper and tmtetlation. Generally speaking, 
studs in good condition should never be removed from 
the cyiiiidcr fciock, as this will occasion wear of; the 

! m m!\w- 

■ V ; rV rV ; ,\vt Ml J! 
: j jr m \\\\i\Kw ill Itl 


•Mi" . ' ■ «... . • • . v .-.•$!:>> 


above d^uui, ui r rcx«Kcocki.i fi nrbcaJ.nnof the • , ^ ^ a *»4 breaks or is stnpped, the 

stud while drying «r how*.' re,;,,, P.,sH^r«vd . nnv .mj imdlcJ. 

The nuts W be sceurdv locked to the uaper Uwrallimtfp of oew studs his been dtftftssal above. 

Mr iv . i v, » v. a ha.-, » s*"\ 

This uevitc « j r.ipcred screw with ^omiiieot.sbarrp 
jggBft ~T il-.dcv *id a h».g for a. Wrench. The extractor is made of 

hardened alfor stfcd 

!v is eitroneU irn|x>frant <h.u tin correct procedure 
be empfoved when tains such a device to remove a 



.. . .... z^- 

Digitize- by i^oogle • 

. * ••-•-.-?r-- "'•w .U-A. *;, S' » 

••/ . . .. '. - ; "t"* ' •• , • 


in some e^es, screw ex tractors are no rait ire.) v sue- 
cestui for the removal q{ broken situji! la such in- 
I hmm*. it i 5. nectary Va dni! uut the stttj and re fan 
thehok, IdtaU.v, tins will he: a'ec*inVpjish«l- h\ ; * jselecc-- 

• flf 

.<A\6.v::. . 

- > •..or HOi.t 


■ v." 


thread th nines* .'Ujmo .v -lection nf i.hc nnrpet size 11E1. General. Cylinder htbd gaskets <ire quire 



,,>H fibre, rubWc, or corobiwtioi* such as ing ^:, h ^; m$r lhi " Micron ha* fecr^ lowed u> 

corwr-citid j*sbcitos g&$km >Scai m g pt otL wartrr,. . - , ^. lini ^ P w ™^ .1^ > u.,^ 

Pulled up to the hftukinu jv»inr N.imruUy, no gasket 

Leaky Cvltnder hctJ gaskets m;*v become upparem should, he frseil that us i-Orn .or /bnrnol across an area 

• * , t : • .' ' . / - ■ ' ; ■/•■'-" ■ 

K*p- 2: 7-:-V ' • •••• :. 


it must be st 
r should he renewed 

renewed is gcacruUv suicd iu the unif ja hard jmj fast nde Geoer.dle s^kuf^ smds. 
on manual. Rubhct jnd libfc gassUcs should he tichreneJ Jboiu halfway the firsr rime chef 

(c) Cantos mtalhftw of gaskcL When placing a . 
gasfcet on the cylinder deck, cite mm he excreted not 
to bend, te;;ir. or break the gasket This usually occurs 
when the Operator attempts ru push d*t gasket' over 
the studs Sottfe gjskets, however, do not surround 


Digitized by VjOUyiC ^ 




12A1. Poppet type valves and assembly. Most 
diescl engines employ the poppet type exhaust valve. 
This type of valve is very dependable, but is subject to 
the following troubles. 

a. possible trouble: 
exhaust valve sticking open 

Sticking exhaust valves are characterized by 1) an 
engine miss, evidenced by low exhaust gas tempera- 
ture; and 2) the noise of the cam follower, push rod, 
and rocker arm as they "float" between the camshaft 
and the valve stem. 

Sticking valves can be a very serious trouble. When 
a valve hangs open it not only prevents the cylinder 
from firing; it is also liable to be struck by the piston 
and bent, making it impossible for the valve to seat 
properly. In extreme cases, not very uncommon, the 
head of the valve will break off from the stem and fall 
into the cylinder. As the piston comes to the top of its 
stroke it will jam, resulting in considerable damage. 
Usually the piston will be cracked and damaged be- 
yond repair; often the cylinder head will become 
battered and cracked, possibly breaking into the water 
jacket. Occasionally the piston will break up com- 
pletely, scoring the cylinder liner and damaging the 
connecting rod. 

1. Causes and prevention. Sticking valves can be 
caused by many things. The more common causes are: 

(a) Resinous deposits left by lube oil. 

(b) Resinous deposits left by fuel oil. 

(c) Weak valve springs. 

(d) Bent valve stem. 

(a) Resinous deposits left by lube oil. Resinous de- 
posits are usually the result of improper lube oil. At 
present, Navy approved 9000 series oils, if available, 
should always be used in diesel engines. The 9000 
series oils are additive type oils that have a detergent 

action. This detergency not only prevents formation 
of gumlike deposits, but is also beneficial in reducing 
any deposit already formed. 

Changing from a nondetergent type of oil to a deter- 
gent type will, in most cases, eliminate sticking valves 
that are caused by gum formations. When initiating 
the use of detergent type oils in a dirty engine, the oil 
should be used for only a short time before changing 
it. Detergent oils will break loose the sludge and car- 
bon deposits on the engine parts. This action will 
pollute the oil very rapidly, and in much less time than 
that specified as the correct interval between lube oil 
changes. For the first two times a detergent oil is 
used in an engine, it should remain in use for only one- 
half, or less, of the usual time. When replacing the oil, 
the filter elements should be replaced and the sludge 
thoroughly cleaned from the filter and strainer cases. 
If possible, all sludge and deposits should be removed 
from the engine crankcase. 

(b) Resinous deposits left by fuel oil. In the same man- 
ner as the lube oil, some fuel oils will cause gumlike 
resinous deposits. The use of the 9000 series lube oils 
will usually counteract this effect. 

(c) Weak springs. Weak valve springs will cause 
valves to hang open more readily when the stem be- 
comes gummy. Weak springs will also allow the valve 
and valve gear to "float" at high speeds, thus reducing 
the efficiency of the engine. Valve springs become 
weakened from normal use; there are, however, sev- 
eral other factors that tend to weaken them. Probably 
the most important is corrosion. Corrosion and rust- 
ing are caused by moisture within the valve pockets, 
and are aided by the formation of dilute acids from the 
small amounts of sulfur present in the fuel oil. Exces- 
sive temperatures will also weaken the springs. 

A broken valve spring will, of course, not usually 
return a valve to its closed position. This is discussed 
more thoroughly under c. Possible trouble: Broken valve 
sprin&s, pages 224-225- 

Digitized by GOOQle ™ 0r '^ ^ 



' ■ ■■ ■ ■ >■ 

id usually' Tcquipa m water 
musi- nfl« he cleaned 
> as they w.iii remove the 
Cure fflnsi he ewased .when handling the cylinder enamel, varnish, of other protective:, eoaf. ng on the 
heads to .nsorc chat the . 'valves are not damaged, springs. 

Setting the '.'bead on spec! or concrete >houid*:lstavoided; , If a valve stem, is hem, the valve must be replaced. 

nick.; seraph, or otherwise damage fbc. valve scan.: show l)lcfei whcK! rus£ , r MlSwft !HlS ujr.ed .K5 uke . 
2 Rtpttif. Slicking v.ives can he remedied i« P*«* Chips rathe enamel or prM.«trvecoacing must 

.. . . . .. ... .... k„ ,.f „,„.L. M,.V, 0 »^ m M „r Wnch.n. 


1 . Causes and prevention. Burned valves are caused by 
one or more of the following: 

(a) Carbon particles between seat and valve 


(b) Insufficient tappet clearance. 

(c) Defective seat. 

(d) Valve head excessively reground. 

(a) Carbon particles between seat and valve head. The 
principal cause of burned exhaust valves is the lodging 
of small particles of carbon between the valve head 
and the valve seat. These particles come from the 
engine cylinder and head when deposits on those parts 
become excessive. The particles will hold the valve 
open just enough to allow the combustion gases to 
pass. The combustion gases pass at high velocities 
and temperatures. This combination causes the valve 
to reach temperatures sufficiently high to cause it to 
burn. Seldom will the valve seat burn under these 
conditions, because there is usually sufficient cooling 
provided by the jackets surrounding the seat to keep it 
below dangerous temperatures. The valve normally is 
cooled by several factors, including its contact with 
the valve seat. When carbon particles prohibit con- 
tact, the heat normally transferred from the valve 
head to the seat remains in the valve head. 

General maintenance of the engine always includes 
frequent removal of carbon deposits. When scraping 
the carbon from the heads, extreme care must be exer- 
cised to insure that all the carbon broken loose is re- 
moved and not allowed to remain in the crevices of the 
head, as later it may loosen and get caught under the 
valves. The scraping tool must not be allowed to nick 
or scratch the valve or valve seats. It is always advis- 
able to remove the valves from the engine when scrap- 
ing carbon. This will permit easy cleaning of the ex- 
haust passages, and facilitate removal of carbon 
deposits from the underside of the valve heads (see 
Figure 12-1A). 

Advantage should be taken of the opportunity to 
inspect the valve stems and guides. Particular atten- 
tion should be paid to the keeper grooves in the end of 
the valve stem, making sure that the keepers and 
spring retaining washers fit properly. 

(b) Insufficient tappet clearance. Insufficient tappet 
clearance will cause burned valves in the same manner 
as described in paragraph (a) above. To prevent occur- 
rence of this, it is necessary to check the tappet clear- 
ance adjustments at frequent intervals to make certain 
that they are correct, and that the locking nuts arc 
sufficiently tight. It is always better to have the clear- 
ance a little greater, rather than a little less, than that 
specified in the operating and maintenance manuals. 

Digitized by GQoQIC 

Tappet clearances vary for different makes and types of 
engines, the values ranging from 0.012 inches to 
0.025 inches. The operating and maintenance manuals 
must be referred to for the correct value for a particular 

(c) Defective seat. The seat is sometimes responsible 
for the valve burning. Most engines are equipped with 
valve seat inserts made of hard, heat-resisting, alloyed 
steel. These inserts generally prove satisfactory but 
will occasionally crack. This allows the hot gases to 
leak, burning the insert and the valve at the same 
time. Sometimes, the metallic contact between the 
valve seat insert and the counterbore is poor. Poor 
contact prevents the heat from being conducted away 
and allows the inserts to gain high temperatures. High 
temperatures cause the insert to shrink and become 
deformed. The result is that both the seat and the 
valve will become burned and require replacing. In 
extreme cases, the gases will pass between the valve 
seat insert and the counterbore in the cylinder head. 
When this happens, the head becomes burned and 
often is permanently damaged. Loose valve seats can 
be avoided only by proper installation. Prior to 
shrinking the insert into the counterbore, the counter- 
bore must be thoroughly cleaned. It should be 
cleaned of all traces of carbon with a steel brush. The 
new insert must have the proper interference, as 
measured at room temperatures. In inserting a valve 
seat, it should be chilled with dry ice, at the same time 
the cylinder head is submerged in boiling water. 
Thirty minutes should be allowed for the operation. 
The insert is then driven into the counterbore. This 
must be done quickly, for the insert will quickly gain 
in temperature and soon reach the same temperature as 
that of the head. A large drift should be used for this 
operation; the seat should never be struck directly. 

(d) Valve head excessively reground. Occasionally a 
valve will be excessively refaced as shown in Figure 
12-1E. Valves that are refaced to such an extent that 
the edge is sharp, or almost sharp, will soon burn. The 
sharp edge is incapable of conducting the heat away 
at a rate sufficient to prevent burning. It is this factor 
that limits the extent to which a valve may be refaced. 
Figure 12-1D shows a valve properly refaced, while 
A in the same figure is a used valve requiring refacing. 
The unevenness of the seating area is apparent in the 

Processes for rebuilding the valve face up to its 
normal level are being developed. Satisfactory results 
have been obtained by welding a bead of Stellite to 
the face, and then grinding until a perfect surface is 




the subject of much 4(>cusv<>« % meat veari The of rati#ie of the -metal. There arc several. hetqn that 
consensu:: or most rcc W \epi«t<W us that in man* cases wiU -increase the rate o| fatigue, anj ..he frequency ut 
i,-. V ■ I .... .u... ... ......... ' tjilurp hv tvrmirfino ..*tt+ss enrir-^rtfrlrifine Wi rvnif 

'. ... the protective owning. This, huwever', ts the' stirt 


are nor readily rcc<j#iuab!c, Swings i and B have Jerigtb is more ibad 3 pet cepf shorrci than the proper 

■broken at one of p.jts. . Whenever a .spring U value, the spring should h; replaced immediately, 

wire brushed, it mikt he thorough! v painted with a 0) Maincenance of protective coxing. Springs 

t^fy/tt cil ■'■ciiMvici \ieJeir& ir A'xwArisiiiUfiiY in fhr .p-npinp. '." ivirh mYtrs-. ctAtks . nr sni-f;ir^ .-iirrrKtriiV mn^ rvivr 

- * & 


itng u^her. caught between rhc .cvlii*tfef head and the piston. 

not strike dither the lock or rhe retuinmg washer, cauj 

When pu'ttifig.thc caps in f face, care mast be taken ro Occasionally the engine mil continue 


l>i i>kcn v,*Ive he ids, aeul tnost 'tt iliem have been dis- 
P§ cussed pre vioMsiv.. They fall into two daswfcs: -those 
uivc "refcuJurT* from mechanic** defomurivn, and those 
been replaced by the newef :scvie C M is a v 4 ;j ve stem caused by fatigue of rhe metal, frtctaf fiujgu* is' 


CcyfhfcjWOfi a net cufljKCt ing rod iriuvif he removed is necessarv to fuive twu exfuusc m arufi »!..'!<, jh uppct 

. the exhaust porr. Therefore, the trapped scavcngnig 

cloy; rhc cxhaUSl port. Supercharge \ai\cs nrr 
provided m the exhaust jumper lines for the purpose 
oi" closing- the exhaust pore at about tin same u?r> fh;u 
the leading cd<>e of the piston closes the incalw pou , 
Geti fbeoinpfessiOii stroke. Actual! ye air will anufflwc 
enter the cylinder unnl the cop prsron nn% ^ur 

v "(.''Miuai iraou 


harge valves are rotating, one for the 
charge valve shaft and one for the lower 
are located at the forward end of ihe 

Fiyvr* Oamag&d valves from cylinder t 

in FtQUt* 12~7A. Br&kaa valve that paused damage 

("d) The iiignhient pi the rod m'iisi be check 


Li k. : i±SL± 

(c) $Wtd or frozen roller fa*rW& The va 

t:xa.y>;rc i>r rtoH titpouti Kyummy carbon depo^ns , replaced vynn .1 rcp.ur imk\ 
•ruv easily obstruct ibv mumm ot the, vah% %n a Tnc halves should op^me >u»m hours before 44 



1 2B1 . Poppet type valves. In four-stroke cycle 
engines, the inlet valves are of the poppet type, 
similar to the exhaust valves. Consequently they are 
subject to the same troubles and failures. Intake 
valves usually give less trouble than the exhaust 
valves, however, due to the fact that they operate at 
a much lower temperature. The intake air valve is 
greatly cooled by the air as it enters the cylinder. 
(See Section 12A, page 221 for discussion of valve 

1 2B2. Ports. Two-stroke cycle engines invariably 
use cylinder ports for admitting air to the cylinder. 
These ports are located sufficiently low in the cylinder 
so that the piston uncovers them as it nears the bot- 
tom of its stroke. The only problem concerning the 
intake air ports is that of keeping them clean, pre- 
venting clogging that results from formation of carbon 

a. possible trouble: 
dirty and clogged intake air ports 

1. Cause and prevention. Excessive carbon deposits 
are formed from lube oil entering the air box. This 
lube oil will come from one of two places: 

(a) Leaking blower shaft seals. 

(b) Worn oil control rings. 

(a) Leaking blower shaft seals. When the shaft seals 
of the blower become worn, the lubricant will be 
drawn into the blower and then be carried by the air 
into the air box. 

(b) Worn oil control rings. Much oil can be brought in 
from the cylinders when the lower oil control rings, 
located at the bottom of the piston, are badly worn. 
Under these conditions there is a tendency for the oil 
passing the lower rings to be wiped into the ports by 
the upper rings when the piston is on the downward 

2. Repair. Formation of carbon about the ports is 
not to be considered an irregular condition any more 
than the formation of carbon within the cylinder. For 
efficient operation of the engine, the ports must be 
cleaned periodically. Access to the ports in most cases 
can be had by removing the inspection plates and the 
hand-hole covers. In some cases it may be necessary 
to remove the intake air header. The cylinder heads 
must be removed in all cases to get all the carbon from 
within the cylinders. It is most advisable to include 
the cleaning of the ports and the air box with each 
carbon scraping operation. This should be done in 

Digitize- by GOOQle ' 

addition to the regular periodic cleaning of the air 
boxes. It will insure that the ports are kept open and 
are able to admit the full air charge in the proper 


12C1. Rocker arms. The primary function of the 
rocker arms, and also of the push rods, is to transmit 
the motion established by the cams and followers to 
the valves, injectors, and starting valves. A secondary 
but important function of these parts often is to carry 
the oil used for lubricating the joints and bearing 

A. possible trouble: 


Most rocker arms are equipped with bushings that 
form the bearing surfaces. These bushings are subject 
to wear and, when worn, make it difficult to adjust 
and maintain the proper tappet clearances. Worn 
bushings are also detected by excess lube oil leakage 
from the bushings. 

1. Cause and prevention. Bushings will wear with 
normal operation. Excess or undue wear, however, is 
usually the result of improper lubrication, which is 
caused by oil passages or loose connections. 

To prevent the occurrence of these troubles, the oil 
passages of the push rods and rocker arms should be 
blown out each time the engine is disassembled. A 
check should be made to see that the oil holes in the 
bushing are lined up properly with the oil holes in the 
rocker arms in order that the lube oil may pass through . 

The rocker arm shaft will also wear, but usually not 
so much as the bushing. The shaft must be checked 
with a micrometer to determine its amount of wear. 
Maximum allowable wear varies for different sizes of 
shafts. The usual value varies from 0.003 inches to 
0.006 inches in most cases. 

2. Repair. Replacement of bushings should be made 
if the wear is excessive. The use of a reamer is usually 
necessary for the final fit. The proper size reamer must 
be on hand before starting the job. 

b. possible trouble: 
excessive wear on pads and end fittings 

1. Cause and prevention. Wear at the points of con- 
tact can usually be associated with pitted, deformed, 
or scored surfaces. This wear takes place on the pads 
and end fittings, and is greatly accelerated if lubrica- 
tion is insufficient, or if there is excess tappet clear- 



ance. Push rods ate usually pdsitjOBed to the cato D. CAM FOLLOWERS AND 

followers and rocker arms by the c«d tunngs TTic LASH ADJUSTERS 

pads are the ends of the rocker arms chat hear on the . . . . - 

valve stem or valve stem cap. When the tapper clear- 12D1 Roller lype cam followers, Tne {unction ot 

ance is excessive, the rods are allowed u> shift around, . thc « m _ fol)owcr ^ » impart motion set up by the 

greatly increase the rate of m of both the rocker « m5h ' ,ii; tw the ^ b fods > fina % t0 

arm and the rod r th*. valves or: iajector -being acmated. 

Thc construction of r.he cam follower is simple uhtl 

2. Ktpw When ficrmgs become ^orn, the push rods ls ,usialiy of either the roller type or the mushroom 

musr be replaced -Continued csc of poor fitting and rype Special caui followers with hydraulic 


• • • • -Titf'pgT wow • — ■ — • • . — 

— - — - - This k the trouble moss csmniooh experienced with 

Worn tappcf ; us t lag screws and lock mi 13 usually roiler rype earn foWowers. Worn rpU^r$ , usually arc 
make it diUkuh to mujiicm'n proper defaces mi to characi.mgeiJ. by- holes and pir marks In che roller sur- 
kcep the rocScrtut? tiglK {ace. Thc roller in mosc instances is made- of case hard- 


- ^ / f \\i ■ '■ J- »?. . sled. Once rhe casc, narJeneit lay er is f>encrr^:red, 

■ tt j J > ) > - •? , j „ complete failure of che roller will rxjo foiiovv. The 

usually caused by <oose ^. ^hen he foe, nuts !ayeHs vcrv ^ and mn , ad whcn (l - ... 

*te to^/the-aditisMg screw, .is -allowed to work up . . . 1 - ■ . ■ - 

and dc W « on the threaSxachnme the valve 1S opened -om trough to .pots, an extremely sharp edge | 

and closed. To prevent the occurrence of rhis trouhte. 

the lock outs must be tightened down after 

.ustment and checked at fre 4 ueot mcervds The fioai , r, g^ t^V^-! ™»*< grower: on 

, . . ~ \. , » > , which the ■ rollers need replacing. - 

check on a tappet clearance ad justment; should be . ■ , * r , > 

, ' , ■ f , - u u , r ■. Consider Able tremble has l^cn experienced- *>n:.dtrcct. 

made thc locking raur has been secured.,; ' . . •■ * . 

rtfverong engmes tn wfttcn the camshan is equipped 

2.. K*/>tf/>. If the threads to the rocker arm' i?.'re '-worn, '. with roc lined pianos bemcco l^bcs. On these engines. 

che entire rocker arm must be rephked- Attempts at the cam fo] lower is expected to slide between ajjom- 

repair, or the use of" a new tappet a<ifusrmg screw,. ing cam lobes Although the edges are rounded, the 

should be resorted: ro Onl>* io tases of em^gei5C>'. case hiudening on these rollers wiJi crack through. 

' leaving a 'razcrUkc ed^c. Jf the roller is continued m 

1tC2. Pmh rodi. Most push rods arc constructed usc chb , fearpc d g e will car into tod cause severed a nv 

esscmiailyof a length ot ho) low rod with end ht%gs^ a(JC ro rhc ^mshah Its.U each nn)r the shaft is shifted 

or cups, fastened in rhwnJs to form a beanng surface /Voiu one position to the orher 

i. C^j/jf W pwnWK NocmiO use will cause sur- . . 

— — ' . , . .... ... 


face disintegration, usually as a result of fatigue of the 
hardened surface. The condition is aggravated by dirt 
or other abrasives. Nicks and dents on the rollers will 
also start disintegration. 

Prevention of this trouble is impossible. However, 
the damage caused by the defective rollers can be 
minimized if the defects in the rollers are found before 
they have had sufficient time to seriously scar the 

2. Repair. A constant watch must be maintained for 
defective rollers, nicks, scratches, etc., in the cam- 
shaft. Whenever a defective roller is discovered, it 
should be replaced at the first opportunity, before it 
has caused damage to the camshaft. 

If any pitting, roughness, or galling is found on the 
inclines between two sets of lobes, the surface should 
be smoothed down with a high-speed hand grinder. 
The cam lobe surfaces must not be ground. This would 
spoil the contour of the cam and make it useless (see 
Chapter 14, pages 277 to 280). No more material 
should be removed than is necessary. The camshaft 
must be removed from the engine before attempting to 
grind the surface. If the grinding is done with the 
shaft in the engine, steel and emery dust will get in 
the engine, and will cause additional trouble. 

b. possible trouble: 

worn cam follower body and guide 

1. Cause and prevention. Worn guides are usually 
caused by abrasive foreign material. When the valve 
gear is disassembled, a check should be made to see 
that the followers move freely and that they arc not 
excessively worn. Particular attention should be 
given to the positioning pins used only on the roller 
type followers. 

2. Repair. Worn guides and pins (usually the roller 
shaft pin) must be replaced. 

c. possible trouble: 


Some engines are equipped with needle bearings to 
eliminate friction in the rollers. These bearings are 
frequently subject to failure. 

1. Cause and prevention. These parts fail due to the 
length of service under normal operating conditions. 
Prevention of the failure is impossible unless the 
rollers are replaced periodically. The important thing 
to remember is that when the needle bearings fail, the 
camshaft is very likely to become scored and severely 

Digitized:, GOuQle 

2. Repair. Replacement of all needle bearings should 
be made at the first indication of flaking or galling of 
the needles. 

12D2. Mushroom type cam followers. Unlike the 
roller type cam followers, the mushroom type is not 
positioned in the guide, but is free to revolve and 
should revolve. Troubles encountered with this type 
of follower all concern the surface condition of the 

a. possible trouble: 
worn surfaces 

1. Cause and prevention. Wear on the surface of the 
cam follower is usually caused by failure of the fol- 
lower to revolve. This allows the cams to wipe the 
same surface each time the shaft revolves. The center- 
line of the follower usually is displaced slightly to one 
side or the other from the center of the cam face. This 
causes the follower to rotate, thus distributing the 
wear over the entire surface. Wear results from normal 
use but is greatly accelerated if the follower does not 
rotate properly. Once the hardened surface of the fol- 
lower is penetrated, it will begin to wear rapidly. The 
worn cam follower will in turn cause considerable 
wear on the camshaft. A check should be made 
to insure that the followers are free to rotate in order 
to minimize the possibility of this happening. 

2. Repair. Faulty cam followers must be replaced 
immediately. The surfaces of the cam involved must 
be checked, and also the lift of the cam. If improper, 
it will have to be replaced. The correct value can be 
found in the instruction manual. 

12D3. Hydraulic valve lifters or lash adjusters. 

The function of hydraulic valve lifters is to provide a 
means for controlling valve gear clearances or lash. 

The lash adjuster can be installed in the push rods, 
rocker arms, or the cam follower. 

Figure 12-11 shows a Zero Lash unit installed in an 
L-head engine. The lifter is composed of the follower 
or body (A), into which the hydraulic unit fits, re- 
placing the usual tappet adjusting screw and lock nut. 

The hydraulic unit comprises the cylinder (B), the 
plunger (C), the ball check valve (D), and the plunger 
spring (K). 

Oil from the lube oil system at approximately 50 psi 
is supplied to the hydraulic lifter through the hole 
(H) to the supply chamber (J). With the face of the 
lifter on the base circle of the cam, and the valve 
seated as shown in Figure 12-11, the light plunger 
spring (K) lifts the hydraulic plunger (C) so that its 
upper end contacts the bottom of the valve stem, thus 

Qrigiral from 


1 ,.L.-.^^^^ 

taking up all clearance and .slack, As the p\un%tt'(C) the supply chamber to; keep if filled 1 As the cam -searts 
moves outward to absorb rhis slack, the b^ii check to lift the followers,, the ml in the cylinder (B) will : 
valve 0>) moves off ii$ seat ao^ allows rbcr oU io tKe tend to pass hack inui th<: suppiv^ bar ibis cendenev 

*\. bat this tendtnev 

supply chamber, which i$ tender ptessare, K> enter rhe wit) firmly seat the baU check (X>) and prohibit tfc from 


ing, and that the lube oil filters must be changed. 

The accumulation of gums and resinous deposits is 
usually an indication of the use of the wrong type of 
oil. Navy specified 9000 series oils do not tend to cause 
gumming, but, rather, are quite beneficial in removing 
and eliminating such formations. 

(c) Check valve seat scored. The condition of the valve 
seat must also be checked. The seat is likely to score, 
in which case the oil will leak past it when under 

(d) Excess leakage due to wear. Excess leakage around 
the plunger can be caused by normal wear. This, how- 
ever, is not the usual case; the damage generally is 
done by foreign particles. 

2. Repair. After discovering a noisy lash adjuster 
and checking to see that the oil supply is plentiful and 
the pressure sufficient, the unit should be removed 
from the engine and disassembled. 

Only one unit should be disassembled at a time. The 
plungers are not interchangeable, and care must be 
taken not to interchange the plungers and cylinders. 
A watch must be maintained for dirt, etc., as it may 
give the clue as to what is causing the trouble. All the 
parts should be carefully washed in kerosene or diesel 
fuel. The following parts should be checked for fit: 

Cam follower body: The body must slide without bind- 

ing in its guide. It should drop under the force of its 
own weight. 

Plunger and hydraulic cylinder. These parts should fit 
closely, but not bind. 

The leakage rates of the check valve and of the 
plunger and cylinder must be checked. To do this 
kerosene should be used. The allowable rates are very 
broad in latitude. 

If kerosene is used as the fluid, the ball check 
valve should not leak more than one drop per second 
when the plunger is loaded with a 50-lb weight. 

When used in a non vertical position, the free travel 
of the ball check is important. Its travel must be 
limited to 0.014 inches. 

When reassembling the units, the plunger spring 
must be snapped into the counterbore. No attempt 
should be made to fill the cylinders with oil. This will 
be taken care of automatically when the engine is 
started. The time required to remove all the air from 
the cylinders is, of course, dependent on the condi- 
tions, but the air can usually be eliminated and the 
valve assembly be operating quietly in 30 minutes if 
the unit is in a vertical position. Forty-five minutes 
should be allowed if the assembly is not vertical. 
When the engine is first operated after work has been 
done on the lash adjusters, it should be run at the 
slowest speed that will develop full lube oil pressure* 

Digitized by GOOSES 

Origiral from 




1 3 A1 . Trunk type pistons. The trunk type of 
piston differs from the crosshead type in that the 
piston performs the function of the crosshead, absorb- 
ing the side thrust and guiding the piston end of the 
connecting rod. Trunk type pistons are used only in 
single-acting engines. 

Figure 13-1 shows a typical trunk piston. In order 
to clarify the discussion, the nomenclature shown will 
be adhered to. 

The design of a piston for a dicsel engine is of prime 
importance. The trunk type piston is required to 
perform several functions. The most important are: 

(a) Provide the moving wall that permits changing 
the volume of the cylinder (crown). 

(b) Support the rings used to seal the cylinder (ring 

(c) Takc the side thrust due to the crank and connect- 
ing rod angle (skirt). 

(d) Provide a means of attaching the connecting rod 
to the piston (piston pin boss). 

(e) Conduct the heat absorbed from combustion 
away at a sufficient rate to prevent excessive tempera- 
tures that would cause the piston to melt or burn. 

(f) Act as a valve in opening and closing ports in 
two-stroke cycle engines. 

The piston is designed with the intention of making 
it as light as possible. This is done to reduce inertia 
forces and hence the vibration of the engine. No sacri- 
fice, of course, in required strength is made to lighten 
the piston; instead, lightweight materials, coupled 
with more efficient structural designs, are used. 

The trunk type piston is subject to the following 
forces : 

(a) Gas pressure, bearing directly on the crown. 

(b) Side thrust, taken by the piston skirt. 

(c) Own inertia forces. 

Digitized by CjOOQIC 

These forces together with conditions of friction, 
heat, and dirt can cause several troubles. 

a. possible trouble: 
worn piston, excessive clearance 

Excess piston-to-cylinder clearance is evidenced by 
piston slap and excessive oil consumption. Piston slap 
occurs when the piston shifts its thrust from one cylin- 
der wall to the other. This happens just after top dead 
center and bottom dead center. Oil consumption in- 
creases as a result of the taper of the cylinder as it 
wears. The taper necessitates that the rings flex at 
each stroke of the piston. This causes excessive ring 
wear which allows the lube oil to pass the rings and to 
be burned in the cylinder, resulting in excessive carbon 
deposits being built up. 

Piston wear is a normal occurrence in all engines. 
The amount and rate of wear, however, are dependent 
upon several controllable factors. 

1. Causes and prevention. Causes of excessive and 
undue piston wear are: 

(a) Insufficient lubrication. 

(b) Improper starting procedure. 

(c) Overload. 

(d) Unbalanced load, 
(c) Dirty oil. 

(f) Dirty intake air cleaner. 

(g) Improper cooling water temperatures. 

(h) Improper fit. 

(a) Insufficient lubrication. Inadequate lubrication of 
the cylinder walls will cause excess wear both on the 
piston skirt and rings and on the cylinder liners. Lube 
oil provides a layer, or film, that tends to cushion the 
piston within the cylinder and prevent metal-to-metal 

Oil is supplied to the cylinder wall by one or more 





, _ ( , " ; / ( \ - ' : s I -\ * . * 

.of. ihe follow mg means, depending on. the engine (3). Mtchawext lubrkMati are generally u*j«l on ferfcc, 
concerned; *j>glc-.icring engines, -and on all double-acting. 

: t'l) Splash frim «» e rodbear^, Most media*- * ^ f |^««ly to tte ^hnjte wUU 

M^hik-^cd cn^nu, receive part of the cruder lhw0 * h sevCT;l1 sma,! hol - S ! - sce ^ « -2)- Tb« oU 

mm i 

Slim ^ 



drop strings out, it Indicates thar tjrc vUcosicv of the iyftl c-juse w^cmtvc loads an the pistons 'tfuailv only 

Vfiitct. h. approaching the vkoosiiv of die Oil. one-ptSfc)!i vvtll be tUmagfciJ and : he da inajft will be 

(K) Aw/w/*r .w«y»x 'proceJart* Possibly tWflt&fcfct caused hv the crJai JijiJT of rbut one cylinder. Such 

wear on the pi's edit' Oixuts when die engine is stared- £verfo:ulfag ts termed m'Uiaffc*, The engine must be 

uxitiarv kite 6tl pumps either hand or ( e W Jvr/y Lube uif iliac js dirty .'.vill cftU^ piston 

eiertncafiv operand On engines so equipped, these and cylinder liner wear The In h: oil most be Icepc 
pump* mu*t be operated for 2 to rahvuves? before turn- . clean and changed ^jead>c;dh'.. -(See Chapter 6 5 Sec- 
the cn^.nc over. This enables oil to circulate, lion pag'es 133-1.36 for jiscus-sian of che proper care 
>Knigb the lahe oil lines and pamges and to. the of lube oil ) 

pans requiring kibiicadon II engines have .been idJe (J) limy intakx ^f dtamr- The air ele^er is prodded 

. for | long period of dm.c 4 ic 2 s. good practice to bar c he to remove dirt and kbrasWe material bom 1 hi air and 
•en^ne ovcr.'ln hand i'Or-.^-cral revohiUon* while the prevent it from entering the cylinders,, Grit and dire 
auxiiian lube' oii pujrtp. are opera entering the cylinder* cause undue wear aad excess^ 

clearance (For program: of air c leaners, see' Chapter 
.2, Secnon D, p*ges 25 -26.) 

must aJ^up be operated within rbe cempcratorc ! \ «>n< 
-'^^hin themstrAicnon rnanuab High cylinder *ur- 

nrsprr tfitri^ **y-*i 11 '.jwl rviry rh** xrlcA'\K-lr%'' *\f t-h," (tilv : 

W CnScudi^t&c cylinder liner'. SuH> vo.i«i,g f^gh-.. 

!«*/• ^ni Rhe.litK.t so ;ss to cause art abrasive scnon <m the 
mnne^udV. sk «" The .aJJeJ beat general rends to 

: . ^scorr.ia.f of the liners and pistons, apd taay' possibly ' 



(a) Obstruction in cylinder. The most common cause 
of cracked piston crowns is obstructions within the 
cylinder, such as broken valve heads, nozzle tips, or 

On several occasions, personnel have left tools, head 
nuts, etc., within the cylinders. The cylinders must 
be inspected carefully before placing a cylinder head 
in position. Openings in the cylinder head, such as 
the injector wells, must not be left uncovered. A 
wooden plug or clean cloth or paper must be stuffed 
into them. 

Damage caused by valve heads breaking off is dis- 
cussed in Chapter 12, pages 227 to 228. Whenever a 
valve head has become jammed in the combustion 
space, it is imperative that the piston crown and the 
other sections of the piston, be examined carefully for 
cracks and other imperfections. A check should also 
be made for bending of the connecting rod. 

Excessive damage caused by parts falling into the 
cylinder can be minimized if the operating personnel 
are alert and shut the engine down as soon as the 
trouble has developed. 

(b) Loose piston. The crown is the hottest portion of 
the piston and, therefore, will expand more than the 
other portions. If it were allowed to contact the 
cylinder wall, wear of the hot crown would be exces- 
sive. It is customary to relieve the crown of the piston 
above the top compression ring so that it will not have 
contact with the cylinder wall. When the piston skirt 
is worn, it may allow the piston to cock sufficiently to 
cause the crown to drag on the cylinder liner wall. 
Most pistons are not designed to take this thrust on 
the crown and therefore cracks are likely to occur. 

When the pistons are removed from the engine, the 
area above the rings should be inspected to determine 
whether or not the crown is dragging. If the appear- 
ance of the surface indicates that it is dragging, it will 
be necessary to determine the cause and to remedy it. 
It must be made certain that it is the piston crown that 
is dragging and not just the carbon deposits that have 
accumulated on the surface. The cause of the piston 
cocking which allows the crown to drag is usually a 
worn cylinder liner. However, the cause is very often 
a combination of a worn piston and a worn cylinder 
liner. The instruction manual should be consulted for 
the correct values of the dimensions. 

(c) Faulty wzgle spray. An improper fuel spray pat- 
tern will cause unequal temperatures on the crown, 
often resulting in cracks. This source of trouble may 
be eliminated by properly maintaining the nozzles. 

(d) Faulty cooling. Cooling of the crown is accom- 
plished 1) by the fresh charge of air blown over the 

Digitized by CjOi KjlC 

crown, 2) by conduction of heat through the piston 
rings and thence to the cylinder wall, and 3) by oil 
sprayed or conducted over the underside. If the oil 
flow is restricted, the underside of the piston will coke 
up with deposits which will lower the rate of heat 
transfer. Whenever pistons are removed, the underside 
of the crowns should be thoroughly cleaned. 

2. Repair. Attempted repair of cracked pistons is not 
recommended. If the crack continues to develop after 
attempted repair, it will cause the entire piston to 
break up and cause serious and extended damage to the 
entire cylinder assembly. Replacement of the piston 
is the only proper repair. 

c. possible trouble: 


The lands of the piston are depended upon to posi- 
tion the rings properly and hold them. Serious troubles 
are encountered when the lands break. 

1. Causes and prevention. Broken lands can be at- 
tributed to the following: 

(a) Insufficient ring clearance. 

(b) Broken ring. 

(c) Cocked piston. 

(d) Excessive wear of piston ring land groove. 

(e) Insufficient cooling. 

(f) Improper piston installation procedure. 

(g) Improper piston removal procedure. 

(a) Insufficient ring clearance. For correct piston ring 
operation, it is necessary that clearance be maintained 
between the ring and the land, and also between the 
ends of the ring, in order that the ring may be free to 
flex at all temperatures of operation. The clearance 
required depends upon the size of the ring and the 
materials involved. Ring groove clearance is further 
discussed in Section B of this chapter. The instruction 
manual should be consulted for correct values for 
particular engines. 

Carbon deposits also accumulate in the grooves, 
causing the rings to bind or stick. When installing 
rings on a piston, the grooves must be cleaned before 
putting on the rings. Carbon solvent or diesel fuel 
should be used for this purpose. Both the sides and 
bottoms of the grooves must be cleaned. Carbon may 
have accumulated on the bottom of the groove to such 
an extent that a new ring may not be able to compress 
sufficiently even to enter the cylinder. The oil holes in 
the oil control ring grooves must also be cleaned; a 
small twist drill will do this quickly. 

After the ring is properly installed, the clearance 



between the ring and the land must be checked. This 
check must be made all the way around the groove, 
not in just one place. To do this, thickness gages must 
be used. The clearance must fall within the limits set 
by the manufacturer. 

(b) Broken ring. On two-stroke cycle engines, a 
broken ring is liable to become caught in the cylinder 
ports. When this occurs, a great force is exerted on the 
land in the vicinity of the port, often resulting in a 
cracked land. The ends of complete rings (not broken 
pieces) have at times caught in the cylinder ports. If 
a ring with insufficient gap is placed in a cylinder, it 
will tend to bind in the cylinder due to expansion, and 
may be forced outward into the ports. This will cause 
initial scuffing of rings and liners, and lead to broken 
rings and eventual piston seizure. 

The catching of rings in the ports is largely de- 
pendent upon the condition of the ports. Burrs, car- 
bon deposits, or other sharp protuberances must be 
removed before installing the piston. 

(c) Cocked piston. The outside diameter of the ring 
land usually should be less than the outside diameter 
of the piston skirt. When the piston and cylinder liner 
become sufficiently worn, the piston may be allowed 
to cock sufficiently to cause the ring lands to drag on 
the cylinder walls. This loads the lands excessively 
and can cause them to become broken. If the lands are 
dragging on the liner, the piston and liner must be 
measured and the cause of dragging determined. The 
usual cause is that both the piston and the liner are 
worn beyond the allowable limit as set by the engine 
manufacturer, thus requiring replacement both of the 
piston and the liner. 

(d) Excessive wear of piston ring land grooves. Excessive 
wear of the rings in the lands will also have a tendency 
to cause land breakage under the hammering action on 
the land. If this condition exists, new pistons should 
be installed. Occasionally the ring grooves are ma- 
chined and oversize rings installed. 

(e) Insufficient cooling. Insufficient and uneven cooling 
will cause failure of the ring lands. The cooling oil 
passages and the undersides of the piston must be 
kept clean. 

(f) Improper installation procedure. Proper care must 
be exercised when inserting the piston in the cylinder 
if ring and land breakages are to be averted. No at- 
tempt should be made to install pistons without the 
proper ring compressor. The piston must be lowered 
into the cylinder gently. A chain hoist should be used 
for large pistons. No attempt should be made to lower 
the piston and rod assembly into the cylinder by hand. 
If the piston rings are allowed to catch on the top of 

Digitized by 

Go gle 


the cylinder, the land holding the rings is likely to 

(g) Improper removal procedure. Ring lands are some- 
times broken while the piston is being removed from 
the cylinder. Before the piston is removed, the area 
of the cylinder above the ring travel must be scraped 
free of all carbon. In some cases, it may be necessary 
to level the metal ridge at the end of the ring travel . 
The ridge should be scraped with a regular steel 
scraping tool. A cloth should always be placed in the 
bore to catch the scrapings. 

2. Repair. Repairs to ring lands should not be at- 
tempted except in cases of extreme emergency, and 
then only when experienced machinists are available. 
A cracked or broken land requires that a new piston 
be used. 

d. possible trouble: 
piston skirt seizure 

This trouble is evidenced by binding of the piston. 
The appearance of the piston skirt will be similar to 
that shown in Figure 13-6. Such galling and scuffing 
of the skirt will often result in the engine "freezing 
up" and possibly breaking the piston and other major 

1. Causes and prevention. 

(a) Insufficient clearance. 

(b) Excessive temperatures. 

(c) Inadequate lubrication. 

(a) Insufficient clearance. Installation of pistons with 
insufficient clearance will result in this type of failure. 
The piston-to-cylinder clearance must always be 
checked before final assembly. The proper value may 
be found in the instruction manual. If the clearances 
are insufficient, the parts must not be assembled with 
the thought in mind that increased and sufficient 
clearances will be gained by "wearing in." Such a 
practice may cause serious results. The clearances must 
be correct when the parts are assembled. 

(b) Excessive temperatures. Piston seizure is often the 
result of overheating. The engine must always be 
operated within the limits established by the Bureau 
of Ships. 

(c) Inadequate lubrication. An adequate flow of oil to 
the cylinder surface is required if the pistons are to be 
prevented from seizing. 

2. Repair. Pistons that have seized within the 
cylinder liner should not be used again unless the 
piston is thoroughly checked and the surfaces refin- 
ished. It is always better to use a new piston if one is 
available. In cases of emergency, the piston should be 

Qrigiral from 

muse be replaced 

,nd f h«.*kr u.t the 5U rf« ft smoothed with a flat Kf ^. A „ cafbafS !a tbc groave , roust bc r6 _ 

hie rh,s ..peranon requ.res tolerable .fall, and <jioved before in^i!,^ tte ,i«^in than. Afer the 

the ring- to- land 
i and the values 
ven ui the imxrucuon 

»"£<>vV*v' -VN'D < AND DRAtiOiNG ,r " nrf * %t !f twill ^ nfvw. 

... - - ' . _ . . . 

On che m*,foriTv r>f pistons now in use, xhe o 

insafficicJix. it is 

tot ir/j*/ frtvtntron. Sec * Possihh p^uhh, War*; 

The oil r»ng grooves ot rhe pitwa are dr. {led thrmigh 
to allow she tube ail wiped from the walk to drain. 

pjitatj. exceim* ctraw/cr, pa#es 235;- '238* 

2 Rcpaty: Repair usually is impossible, inasmuch ° 

muse always be operated within specified limits 

bustling is caused cither by ,i lack of lube oil pressure 

rmer i& not (ike! v 

to cause serious damage, *;nceohe loss of pressure will 
be noted on the utstruxneaus before .my great harm wiiJ 
have been dope to the piston pin and bushings. Clogged . 
lube oil piiss*igc5 will, otv the other .baud, have no 
reco^ni^Wc symptoms. Hence, a* re and diligent 
must be cwxmd when inspecting rbc piistaa *«d con- 
necting rod bdore assembl nig. 

Tbel^shmg position in the pwan m^st always Be 
chec ked. The oil bole in she bushing .most dine up 
with the ad passage in the boss. A wire should be 
passed through rbe passageways to insure rhar the} 
are open. The pa$sa£*A\\*vs of the connecting rod musr. 
also be checked, When installing the connecting rod 
hearings, n must be made certain that the beano*: 
>liei)s are placed so that the oil boles ime up properly. 

(b) £:<nsi thnp varum'. The engine must always be 
operated within t he required temperature range for 
cylinder cooling water (see Chapter 7) The piston 
pin bushing most of its cooling from the 
piston coolant., usually lube oil, and there; rnusr be. ;i 
free. Row of the coolant to " the piscoa 

¥%g%ttm 13~7* Piston ruinsd by ci$gg&tt <wV botes apd $*r#* 

the engine wdl greadv stress the piston boss bushings, 
(c) Improper tffi Use of the improper lubricating oil The engine must not be overloaded except in eases of 

ieizvf*. : fey<Qi'trlQfui find tvihalance vf tttpnc* Overloading of 

the piston. The. clearance between bushing and pm 
jtjuu be checked to Jctominc of it is within the sped* 



piston and piston Tiki .iSSCOll lv 


(a) Imnfficimtt Jxkrtmh** The piston skirt and ring* ] 

excessive csrbon deposits. The norin.ij race of Haw of 
lube oil at rated speed .s .rv-oficd in the imiroccwo 
manual. The drops of oii art observed through m 


visablc that the sight gages be carefully observed at 
least once each four-hour watch. At the same time, the 
level of the oil in the cylinder lube oil tank should 
be checked. 

The lube oil lines are connected to the cylinder lube 
oil check valve assembly. The function of these check 
valves is to prevent the gas pressure within the cylin- 
der from being exerted upon the lube oil in the lines, 
thus making it impossible for the lube oil to get into 
the cylinder. In some cases, the check valve assembly 
has loosened and allowed the jacket water to enter the 
cylinder. Other cases have occurred where the gasket 
has become damaged and water leakage has resulted. 
Whenever the lines are removed from check valve as- 
semblies, advantage should be taken of this oppor- 
tunity to determine whether the valve is tight. If 
water is ever found in the cylinder of an HOR engine, 
the first place to look for the trouble is in the cylinder 
lube oil check valve assemblies. 

(b) Overload. Operation with the engine overloaded 
will increase the rate of wear of the babbitt band. 
Higher operating temperatures are encountered at 
overload conditions and tend to soften the babbitt. 
Diesel engines should not be overloaded unless a con- 
dition of emergency exists, and then only as long as 
the emergency exists. 



Figure 73-70. Cylinder lube oil check valve. 

(c) Overheating. Care must be taken to prevent the 
piston from overheating. The only indication of the 
piston temperature is the temperature that the lube 
and cooling oil attains before entering the oil cooler. 
The piston is cooled with lubricating oil that is 
pumped through the piston rod and piston by a posi- 
tive displacement IMO pump. The temperature of the 
lube oil leaving the engine should be maintained 
within a range of 140°-180° at all engine loads and 
speeds. The cooling water high temperature alarm 

Digitizes by ("jQt. iQlC 

should be so regulated that it sounds off when the 
temperature reaches approximately 185° F. Inability 
of the coolers to keep the lube oil at the prescribed 
temperature indicates that the cooling system, and 
the lube oil cooler in particular, require servicing. 
(See Chapter 6 for trouble and maintenance instruc- 
tions for oil coolers.) 

(d) Worn rings. Excessively worn rings will allow 
the combustion gases to pass the piston skirt. When 
this occurs, the gases tend to heat the piston skirt 
excessively. Combustion temperatures are above 550° 
F. Since babbitt begins to melt at about 450° F, the 
babbitt band is likely to reach its melting temperature 
if much blow-by is encountered. 

(e) Broken rings. Piston rings sometimes get caught 
in the cylinder ports, and in so doing, are broken into 
small pieces. These small pieces of rings score, and 
sometimes become embedded in, the babbitt material. 
To lessen the damage caused by broken rings, the 
rings should be inspected at frequent intervals through 
the sight glasses or inspection covers in the intake 

2. Repair. Worn and damaged piston skirts must be 
replaced. Attempts at rebabbitting the piston skirt 
should not be made in the ordinary shop. Before the 
piston is replaced in the cylinder, the port openings 
must be checked. They must be free from any burrs or 
other protuberances. The piston skirt-to-cylinder 
clearances should also be checked. 


13B1. General. Piston rings fall into two general 
classifications, compression rings and oil control rings. The 
three functions that the piston rings are required to 
perform are: 

(1) To seal the cylinder and combustion space, thus 
preventing leakage of the compressed gas within the 
cylinder. This is accomplished principally by the 
compression rings. 

(2) To control the lube oil on the cylinder surfaces 
in such a manner as to prevent excess oil from getting 
into the combustion spaces, hence reducing lube oil 
consumption. This is accomplished principally by 
the oil control rings. 

(3) To aid in the removal of the heat absorbed by 
the piston crown. All piston rings conduct heat from 
the crown to the cylinder walls. 

The majority of piston rings are made of cast iron, 
and all are of similar design. Different types of end 
joints are employed: straight cut, step, and diagonal, 
as shown in Figure 13-12. 

Qrigiral from 






Figure 13-11. General types of piston rings. 

A. possible trouble: 


Compression leakage, resulting in low compression 
pressure, will cause hard starting, loss of power, 
smoky exhaust, waste of fuel, excessive use of lube oil, 


Figure 13-12. Common types of piston ring gaps. 

Digitized by 

Go gle 

Figure 13-13. Piston ring nomenclature, 

and poor engine operation in general. Low compres- 
sion pressures are detected by regular periodic tests 
and by trouble shooting. The checking of compres- 
sion pressures should be a part of the regular routine of 
every engine room force. Methods of taking the pres- 
sure readings vary with each different engine. The 
instruction manual should be consulted for the best 
method for a particular engine. 

Low compression pressures are not always the result 
of worn piston rings and cylinder liners. 

Other factors that can cause low compression pres- 
sures are: 

(a) Leaking cylinder valves. 

(b) Faulty injector gasket. 

(c) Faulty cylinder head gasket. 

(d) Leaking after-chamber valves. 

(e) Clogged intake ports. 

(f) Intake air header leakages. 

(g) Faulty blower. 

(h) Clogged air filter. 
When a cylinder with a low compression pressure is 

located, the possibility of the cause being one of those 
mentioned above must be eliminated before any step 
is taken to disassemble or replace the piston rings. Of 
the causes listed above, (a) to (c) are causes that 
would affect the pressure in only one cylinder of a 
multi-cylinder engine, while (f) to (h) are causes 
affecting all cylinders, or at least a group of cylinders. 

1. Causes and prevention. Excessive piston ring wear 
can be credited to one of the following causes: 

(a) Inadequate lubrication. 

(b) Excessive piston heat. 

(c) Rings damaged during installation. 

(d) Ring-to-groove clearance insufficient, 
(c) Dust and dirt in intake air. 

(0 Dirt in lube oil or fuel oil. 

(g) Rings stuck in grooves. 

(h) Worn cylinders. 

(a) Inadequate lubrication. Piston ring wear and 
cylinder liner wear go hand in hand. Insufficient 




lubrication will add greatly to the wear of the rings. 
The subject of piston lubrication is discussed in Chap- 
ter 13, pages 235 to 236. The lubrication problem 
affects equally the piston and the piston rings. 

(b) Excessive piston heat. Excessive piston heat will 
cause rapid piston ring wear by causing the piston ring 
grooves to become caked with carbon, preventing free 
movement and expansion of the rings, thereby pre- 
venting the rings from following the cylinder contour 
and properly sealing the cylinder. (See c. Possible 
trouble: Sticking rings, pages 250 to 251.) 

(c) Rings damaged during installation. Many rings 
are ruined before they are ever run in an engine, due 
mainly to the inexperience of the man on the job. 
Piston rings, while not exactly delicate, should be 
handled with reasonable care. The damage usually 
occurs when the rings are being placed in the grooves 
on the piston, or when the piston is being inserted in 
the cylinder bore. 

(d) King-to-groove clearance insufficient. This will 
cause the rings to stick. Hot gases passing the rings 
will cause deposits which will stick the rings even 
tighter. One of the principal forces that hold the 
piston ring against the cylinder wall is the gas pres- 
sure itself. If the ring-to-groove clearance is insuffi- 
cient, the gas pressure will be unable to get behind the 
ring and force it out, thus increasing the probability 
of gas leakage. 

(e) Dust and dirt in intake air. Improper maintenance 
of the air filters will allow abrasives such as dust and 
dirt to get into the cylinders, where damage to the 
cylinder, pistons, and rings will result. 

(f) Dirt in lube oil or fuel oil. This can be responsible 
for excess piston ring wear. However, this usually 
causes severe trouble in the bearings or fuel injection 
pumps and nozzles long before the effect becomes 
noticeable on the piston rings. See Chapter 6, pages 
135 to 136 for information on the maintenance of lube 
oil filters, and Chapter 4, pages 92 to 97 for notes on 
fuel oil strainers and filters. 

(g) Rings stuck in groove. This cause is discussed 
separately as c. Possible trouble: Sticking rings, pages 
250 to 251. 

(h) Worn cylinders. The condition of the cylinder 
bore is of prime importance and is probably the great- 
est factor affecting the wearing of the piston rings. 
Not only is the surface condition important, but also 
the amount of taper, and out-of-roundness. 

Excess taper causes the rings to flex on each stroke. 
This flexing adds greatly to the wear of the rings. New 
rings installed in cylinder bores having excess taper 
should not be expected to give satisfactory service. 

Digitized by 

When the cylinder is out-of-round, new rings cannot 
be expected to seat as readily as in a circular bore. By 
placing all ring gaps above the piston pin bosses, the 
ring is in the best position to make allowance for the 
cylinder wear. Gaps of adjacent rings should be 
staggered 180 degrees to reduce gas leakage through 
them. If the rings have diagonal gaps, the direction 
of the slope of the gaps on adjacent rings should be 
alternated. See Chapter 11, pages 199 to 208 for a 
complete discussion of cylinder liner wear and how to 
measure it. 

2. Repair. Worn piston rings cannot be repaired. 
They must be replaced with new rings. Care must be 
exerted to insure proper installation of new rings. 

Installation of piston rings involves considerably 
moreskill than at first presents itself. Proper installation 
starts at the beginning of the job when the piston and 
connecting rod are being removed from the cylinder. 
The piston must not be removed from the cylinder 
until the cylinder surface above the ring travel area 
has been scraped. All carbon should be removed, and 
if an appreciable ridge is present, it will also be neces- 
sary to remove the lip of it before removing the piston. 
The ridge must not be removed by grinding as this 
will allow abrasive particles from the stone to reach 
the engine. This abrasive matter is one of the most 
damaging things that could possibly get in an engine 
as the hard particles will scar and damage the pistons, 
cylinders, bearings, and all other moving parts. The 
ridge must be removed by scraping it with a steel 
blade. A cloth should be placed in the cylinder to 
catch all metal cuttings. The lip of the ridge on the 
cylinder liner, which in most cases is made of cast 
iron, can be quickly leveled off by scraping to allow 
the rings to slide over it. If the size of the ridge war- 
rants it, the liner should be removed from the cylinder 
block after the piston has been removed and then the 
job of removing the ridge finished. With the cylinder 
liner removed from the block, it is permissible to 
either hand stone the ridge or to use a power grinder. 

The actual removal of the piston should be accom- 
plished by using a chain fall, or if none is available, a 
small block and tackle. This, of course, applies only 
for larger engines where the piston crown is provided 
with a means of securing a hook eye. On small en- 
gines, the pistons can be removed by hand, but even 
then, any block of" wood that can be utilized to aid in 
raising the piston should be used. 

After the piston and connecting rod have been re- 
moved, it is necessary to remove the piston pin. When- 
ever the piston and connecting rod assembly is re- 
moved from the engine, it is advisable to check the 


jl rooJ similar w that showrnu Figure IV U- Thi^ rvpc 
of tool bai a 1 
can be spread, i 

|P Oh || shopkler.. When such , ond-uo,: ,.x 
Ff0</r* 13-15 Uvmj m*r*f strips io r*m**t piston rings. 18 ^ mi ^ l P**«W fcUouM be repjrjtm] Th* only wjv 

J 3-150 The first smp is placed under the open ring at to put it in a lath* and tpm the ri«s Uad* down. Th«. 
the ring gap, slid around the piston a short distance, of cours*. RtcrsMfates the use of <wwrs»r r»nv< Th.v 

U «h the *i P problem careJ tor. rhc ritfg should 
thou be installed un rhc piston, 'fools ?imil:ir to ;!•••';.•-■ 

■ ii 


shown in Figures 13-14 and 13 15 ate atiri used to 
••I- ' • ifefrl'l new nfcfgs. When iiisullpg the ring,, err ; . 

^ivuiu ,w» av* »V4V*v . •* nv" j.rt^r.'H 'in,..' vor - r - r - • — ..- / . .7* 

WKrittaltal should be inspected carefully- to determine '«P<t *> M n ap k> the a>p compr^sjrun ring After the 

ii there are a ay burrs or irregularities on them. Any n&g* are in the groove^ cfic clearance between the 

burr should be smoothed with j rkc. hJe r The nag rmg .md the ljnd musr be cliccked, It . must be checked 

fall within the limits given in the instruction tonal wines, InsuArttent ring-to^md clearance' is apt to 

P,sron vm& ms ™*y be excessive when the ring ,s at tad.e the rings to seif| late*, insu/hocnt clearance 

the top uf Cylinder. After determining the gap usually means rhar the grooves are not cfeaa arid that 

wi?h rhc tin* at the top of the cylinder, the nnc is carbon deposits still exist Oemtonally rhc dimen- 

^:..i^J ... .1.1 1 il " J c,„„c ^ Vh» nn,r .'^r.^, „V f M ^^^^h U 

gap tnan uiat spcaiicq in tne instruction 

manual, the end, of the ring w,!i have to be hied until 
the proper gap is obtained. A straight cue null file 
should benzol toy this, ojfctfiion If the gap dtauges 

cylinder, ic is an mdicavton there k a Certain 

/3-78. tnstollmg piiton in cy»W»r W» wifA fot*«*l 


I" ^.>SP 111 | ...... .... 

so, the ring should be checked vwb. a* small .micro- return grooves*. If the wire catches t« the groove, 
meter. If the groove is too small for the available hcavia-wtresho'dd be used. With a. steady pull or? the 
rings, a set of proper! v btti»a«u*s >hould be obtained. end of the wire, tfwrusgcao be eoa^tniei sulTtctwrly 

piston may be dropped. If rh« pisiQUM provided with Worn oil ' rings are evidenced by excessive lube oU 
a means for insetang :i scrrw eye. it should be sup- consumption> An j by the formation of cxc«s «r&on 
ported bv a chain fall. If it is nor so eoWPPed. some •„ .ti ^,i;„j„.,,^,„„ -it 

Ffew* 13-19 Using wire to «»f off pision ring,. FiW CWfc,„g for iJucfc rings. 

• . Go # BNn ' ' 


M ' «,^M*ii*iiM 


cated by low pressure gage readings. If the defective 
piping is exterior to the engine, the bilges will usually 
contain a considerable amount of lube oil. 

(d) Improper oil. Use of the improper grade of lube 
oil may cause excessive wear and high temperatures. 
The instruction manual should be consulted for the 
proper grade and viscosity. 

1. Causes and prevention. Oil control rings will wear 
under normal operating conditions. The rate of wear, 
however, is greatly accelerated by several factors. 
These are discussed under a. Possible trouble: Worn 
compression rings, page 245- The material discussed 
there also applies to oil control rings. 

2. Repair. See 2. Repair, page 246. 

c. possible trouble: 


Sticking rings arc evidenced by loss of power, 
smoky exhaust, excessive lube oil consumption, and 
sometimes by fumes caused by blow-by of the combus- 
tion gases coming from the crankcasc. Sticking rings 
will result in low compression pressures and can be 
found through periodic tests of the compression pres- 
sures. In most two-stroke cycle engines, it is possible 
to check the rings through the cylinder ports. This is 
done by barring the engine over until the ring is oppo- 
site the port opening. With the aid of a piece of wood, 
the ring can be compressed in the groove through the 
ports. If the ring shows discoloration and does not 
move freely in the groove, some action must be taken. 
The action is dependent upon the severity of the case 
and the cause of the trouble. 

1. Causes and prevention. Sticking rings arc caused 
by one or more of the following: 

(a) Improper ring-to-land clearance. 

(b) Insufficient ring pressure. 

(c) Excessive operating temperatures. 

(d) Improper lube oil. 

(e) Improper installation. 

(a) Improper ring-to-land clearance. One of the princi- 
pal causes for sticking rings is an insufficient amount 
of clearance between the rings and the lands. A set of 
rings should never be placed on a piston without first 
checking every ring for the proper clearance. See 
2. Repair, page 246. 

(b) Insufficient ring pressure. The natural forces of the 
ring tending to spring it out against the cylinder walls 
are required to make the initial seal of the ring. Later, 
the seal is reinforced by the gas pressures within the 
cylinders. If the ring is scmicol lapsed, it will not seat 

Digitized by 

Go gle 


with the proper force, nor will it be able to overcome 
any slight binding of the ring in the groove. Rings 
become weak from extended use and from overheating 
of the engine. A check on the condition of the ring 
can be made by measuring the free gap of the ring. 
Some instruction manuals give the proper value for 
this gap. If not, the gap should be compared with 
that of a new ring. 

(c) Excessive operating temperatures. Excessive op- 
erating temperatures will cause the lube oil to oxidize, 
leaving carbon deposits on the rings and in the 
grooves. Operating temperatures should be watched 

(d) Improper lube oil. Some lube oils when used in 
diescl engines cause resinous gumlike deposits on the 
many engine parts. These deposits have often been 
referred to as engine varnish, carbon, gum, and so forth, 
and when present on rings and in the ring grooves, can 
be responsible for sticking rings. Navy approved 
9000 series oils, however, do not cause such deposits. 
In fact, they have detergent properties making them 
beneficial in the removal of such deposits. 

(c) Improper installation. The task of putting a set of 
rings in an engine is an important one. While it may at 
first appear to be the simple operation of putting the 
rings on the piston and returning the piston to the 
cylinder, it involves much more, as described in 2. 
Repair, page 246. 

2. Repair. Stuck rings should be remedied by remov- 
ing the piston from the engine, and then removing 
the rings from the piston grooves, so that all parts can 
be thoroughly cleaned and checked. 

Mild cases of sticking rings, where it was felt that 
possibly the lube oil was at fault, have been remedied 
by changing the oil and refilling with a 9000 series oil . 
The oil must not be allowed to become overloaded 
with carbon particles. It must be changed at intervals 
as specified in the instruction manual, or an analysis 
made of it. 

Rings securely stuck in the grooves should first be 
soaked in carbon and lacquer removing compound 
(Fed. Std. Stock Cat. No. 51C-1 567-56). If time per- 
mits, the piston should be allowed to soak overnight. 
If the compound is not available, kerosene, or diesel 
fuel may be used. 

If soaking does not free the rings, it will be neces- 
sary to drive the rings out with a brass drift. Consider- 
able care must be taken to insure that the piston ring 
lands are not damaged. The end of the brass drift 
should be ground in such a manner as to allow it to 
reach the ring without contacting the lands. 

After the rings have been removed, the grooves 

Qrigiral from 


must be thoroughly cleaned and inspected for cracks 
and burrs. 

d. possible trouble: 
broken rings 

Operational evidences of broken piston rings are 
hard starting, loss of power, excessive lube oil con- 
sumption, and possibly the emission of smoke from 
the crankcasc breather. 

Broken rings can be found on two-stroke cycle en- 
gines by inspecting them through the intake air ports. 
Quite often, broken rings have all the appearances of 
stuck rings, being blackened by the gases passing 
the ring. 

Serious trouble often results from broken rings. The 
broken portions, if sufficiently small, arc likely to 
catch in the cylinder ports of two-stroke cycle engines 
and thereby cause severe damage to the piston and the 
cylinder liner. 

1. Causes and prevention. Broken rings may be caused 
by one or more of the following: 

(a) Cylinder liner ridge. 

(b) Cylinder port protuberances. 

(c) Insufficient gap clearance. 

(d) Insufficient clearance behind ring. 

(a) Cylinder liner ridge. The ridge formed by the 
wearing away of the cylinder liner material near the 
top of a used cylinder liner can be the cause of ring 
breakage. It affects the top ring on the piston, some- 
times called the firing ring inasmuch as it is exposed 
directly to the combustion gases. While the ridge may 
not cause damage to an old set of rings, new rings if 
installed will travel higher in the bore by an amount 
equal to the wear of the old rings. Should main or 
connecting rod bearing inserts be replaced with new 
ones as well, the piston will travel higher in the cylin- 
der by an amount equal to the total wear of all the 
replaced parts. Not only is this ridge likely to cause 
breakage of rings, but it can also cause breakage of the 
piston lands. 

To avoid this trouble, it is necessary to remove the 
ridge from the cylinder when replacing the rings. The 
ridge should be removed before removing the piston. 
(See 2. Repair, page 246.) 

(b) Cylinder port protuberances. It is felt that most 
piston ring breakages in ported engines are caused by 
the rings becoming caught in the ports. This condi- 
tion is made more severe if any protuberances are in 
the vicinity of the ports. Most ports are chamfered to 
help correct the tendency of the ring to become 
jammed in the port. Every precaution must be taken 

Digitized by G<X 'SlC 

to be sure the ports are not damaged at the cylinder 
bore surface. The ports can be quickly checked by 
rubbing a finger over them. All burrs should be re- 
moved with a small file. 

(c) Insufficient gap clearance. This will cause undue 
loads to be placed on the ring, and will tend to cause 
the ring to be forced out and into the ports of ported 

To determine whether of not the gap clearance of a 
broken ring is insufficient, the ends of the ring should 
be inspected. If the gap is insufficient, a bright spot 
indicating contact will be found at each end of the ring. 

Rings should never be installed in a cylinder with- 
out first recording all the measurements of the gap and 
ring-to-land clearances. Special attention must be 
given to insure sufficient gap clearance at both the top 
and the bottom of the cylinder bore. 

(d) Insufficient clearance behind ring. The function of 
a piston ring is not to support or to position the piston 
in the cylinder bore. There must be clearance behind 
the ring at all times. If not, the rings arc likely to 
become loaded by the inertia forces and by the side 
thrust on the piston. These forces should be borne 
solely by the piston skirt (trunk type pistons). 

Factors causing the ring to bear on the root of the 
groove are: 

(1) Carbon deposits on rings and in grooves. Carbon 
deposits will occur in most engines to some degree. 
When replacing rings, always thoroughly clean the 
grooves, for while the carbon deposits in the groove 
may not interfere with the old worn rings, they will 
interfere with new rings. 

(2) New rings installed must be of the proper depth. 
The correct value for a particular engine is given in the 
instruction manual. 

(3) Worn piston skirts and cylinder liners often 
allow the piston to cock to the extent that the crown 
and lands will drag on the cylinder walls. If the depth 
of the grooves is insufficient, the rings will be required 
to take some of the load and, therefore, be subjected to 
breakage. Some of the smaller high-speed diesels are 
equipped with flat spring stock behind the oil control 
rings, sometimes called marcels because of the wavy ap- 
pearance of the spring. These marcels increase the force 
of the oil control rings on the cylinder surface. Care 
must be taken to insure that the marcels are installed 
in the proper grooves. These oil ring grooves are of 
extra depth, to accommodate the added spring. Should 
the spring be erroneously placed behind a compression 
ring, it would limit the amount the ring could be com- 
pressed, and probably make it impossible to insert the 
piston in the cylinder bore. 



1.. l\ep**r, Bmktn ring<. cannot be J. They sldmMe trouble hasJ>eco,cxfJjerienccd with i.tnpToperJy' 

must, however* be rep) aee.d -j turned htdy .upon their ..assembled nceuie ■ hearing .■ In several Gajk$y adc4k 

discovery. The broken ring itself is not a scnuus bearings have been repi iccUvuh bi^hinxv Due wicaj 

buraklejr: It 'may. buwever, be thecan&e of consider- simpler coasiroaiqn. the bulbing k- Jev* sifyfcet to 

#bte additional darn age, A piece of the ring if caught ire- pro per .ins-uihiuon. 

in a port, will break the. piston and probably score the PHsron '-pisVs are oi^dc of hardened steel alloy, with 

cylinder Hncf. There, h no limit la the ai.riOMnt of surfaces hushed ro a hi^h degree of perfcettoa. Piston 

^S^pipi ... ^ + ... .... .. 

continuing to operate. the eogme. An engine should *• *omm* trOumj*; 

ncv« be .pwd when it is known that one or more . wosn piston nm 

oftbermgs ^broken, except ixianexcreincemcr^Ky. j. C^« ^ Worn piston pins may be 


Pin BEARINGS <h>i^xi^ilbbricari^ 


)kmt\t\$ before 

ISO, General. Pisron pins and piston pin bear- (^Overloading. 

lngsgcn^raHy-re^pJj^ a nnmmuni amount of ;utcntioa (d) Misalignment of rod. 

Instances of. total' failure of ihc*c parts are not mmier- '(a) Ntf^*/ Most piston pin wear is caused by 

ops, Piston pin bearing may be of two types, either normal operation,. U is often thought rhat such wear 

die item hu;Mn$ c?r ihtMeMt. tearrtgf&p Figms. 1 3H2'I). should be *It£ht, compared to other hhafxs. >;uch isth* 

The adraotagc of tfo hecdk bearing ;.bv£r. rhe much crank and tvaiti heauntf journals, and hit this reason, 

-jumpier aud kss ckperi&ii'v:c 'bus hi ng ; is. that ths bashing operating -personnel often, neglect to give tiiem the 

cycle engine when the piston pin 
worn different from that of the crank and main bearing 

.Satisfactory needle bearing operation can be oh- journals. The on i v. loading is necessarily" high because 



the engines must 

to install -the bearing thefts correal v.'The ins true rioa . Improper tobcibttoa, 

ntaoua! should alw^vs .be consulted for infoniurioo (b) Needle bear mg "ftfturc. 
upon ioterchangeabibrv*. 

the pins occurs more frequently wheiuieedle bearangs corresponds to the size of the irtsidc wc^gmeter 

ii\$imcgatt r .ii is ably a *hort timc-unsrif surface fail- wear limit chart (guSfcips Pjan K r o-.S41:0S-589.6Z), If 

cause rapid wear both ot piston l 
is apt to 
creased wear 

anctfei ri%$, Th is 

nccring rod or the pis rem bosses; To do this; the proper 

. ....... .- , .... ..... • . . . . - %g 

avoided except in extreme cases of emergency 

bushings should first be pressed out 'with a mandrel, 
the ;flcccs&tfy force being applied by an arbor prtas. It 

2. R^r. It -will be neces^^place both the & ^ ^ siWc to rcmovc the bushfngs wuh dry ice 


and then inserted in the contxectiog rod cve> 

After the new bushings have -been .ici^iind in the 
vxmnectmg rod and ptsron, che connc^dng rod, piston 

2. Repair, When disassembled, the arnoum of wear 

journal and piston y : tn hcarn^ as vycU as of the piston 

|| for a 



D. possible trouble: 


Worn needle bearings can be located during engine 
overhaul by measuring the diameter of each individual 
needle bearing with a micrometer. The correct and 
limiting values of the needle diameters may be found 
in the instruction manual. It is also necessary that the 
surface condition of each be closely inspected. // any 
surface pitting is found, or wear on any individual needle is 
found, the entire set of needle bearings must be replaced. 
They are never partially replaced. 

1. Causes and prevention. Causes of needle failures 
arc as follows : 

(a) Dirty lube oil system. 

(b) Overload. 

(c) Needle bearings interchanged. 

A more complete discussion of frictionless bearings 
may be found in Chapter 16. 

(a) Dirty lube oil system. The clearances involved in 
needle bearings are very small. Therefore, any particle 
of dirt that enters the system is likely to cause the 
bearing surfaces to become pitted. This condition is 
more serious in a needle type bearing than in the usual 
journal bearing, inasmuch as the needle bearing is 
incapable of imbedding any of the particles found in 
dirty oil. 

(b) Overload, The unit load on the needle bearing is 
very great, due to the fact that the area of contact is 
very small. Overloading of the engine should be 
avoided as it will add greatly to the already highly 
loaded bearings. 

(c) Needle bearings interchanged. One of the most 
usual causes of worn or damaged needle bearings is 
that the individual needles from one set are inter- 
changed with those of another set. Unless the diam- 
eters of the needles in a set are all exactly the same, the 
larger ones will support the load. This means that the 
larger ones are overloaded. This type of overloading 
quickly leads to failure of the entire needle bearing. 
For this reason, it is necessary that all the needles of 
each set be discarded whenever any of them becomes 
damaged or worn. When disassembling a needle bear- 
ing, it is essential that great care be taken not to drop 
or lose any of the needles. All the needles for each 
bearing should be kept together in a separate container 
provided for each individual bearing. 

2. Repair. There is no repair for the needle bearing 
that is worn or damaged. Proper maintenance of 
them, however, as given below, will increase their life. 

(1) An arbor should always be used when assem- 

bling or disassembling a bearing. Care should be taken 
not to drop any parts. 

(2) All parts should be cleaned thoroughly in a 
cleaning solvent, and allowed to dry on a clean cloth. 

(3) Each needle bearing must be inspected for surface 
irregularities. The diameter of each needle bearing 
must be measured with a micrometer. If there is any 
variation in any of the needles, the entire set must be 
replaced. The replacement of one or more needles in a 
set, with even a slight difference in size, will cause 
total failure of the bearing. This may result in serious 
consequences to the entire engine due to steel particles 
of the needle finding their way through the lube oil 
channels to other bearings. Surface failures are often 
caused by fatigue of the metal. The fact that one 
needle has failed is an indication that all the needles 
are about to reach their limit of useful service. 

(4) When assembling the bearing, care must be 
taken to insert all the needles. A heavy grease may be 
used to hold the needles in place during the assembly 
operation. The arbor provided must be used, and it 
must be wiped free of all dust and dirt. If no arbor is 
available, it is probable that one can be improvised. 


13D1. General. The function of the connecting 
rod is to transmit the reciprocating motion of the 
piston to the crankshaft. The rod may be connected 
directly to the piston, which is the usual condition for 
single-acting engines, or it may transmit the motion 
through a crosshead, as in larger engines and in double- 
acting engines. Connecting rods in general are of the 
two types shown in Figure 13-25. 

Connecting rod troubles usually involve either the 
connecting rod bearing or the piston pin bearing. 
Troubles encountered with these parts are thoroughly 
discussed in other sections of this book. For connecting 
rod bearing troubles, see Chapter 15; for piston pin 
bearing troubles, refer to Section C of this chapter. 

a. possible trouble: 
misaligned rod 

Misalignment of the connecting rods can be re- 
sponsible for several troubles encountered with the 
piston-connecting rod assemblies. A misaligned rod 
will cause binding of the piston, piston pin, and the 
connecting rod journal bearings. This binding is 
likely to result in breakage and increased wear of the 
parts, leading to total failure and possibly damage to 
the entire engine structure. 

Digitized by COOQle 




of the m$int irw>! nti$ rbx piston* tyliri Jcr t qr pranfc> 
shAft; it 'is TO^f io cteck the iiligameui of the 

fe/5££s5 « • % - ->• • 


• '• '• ; Eft 


discover -.tracks is a magnetic one, wherein the rod h age w the engine Whenever che rod bol ts are removed, 

strongly iruzneuu\\ and then dusted with a magnetic the. boJ.t threads shoufd be inspected m sec that thev 

•powder, such as cobajt. The magnetic powder is mm*: do mn tend to /*■<> »r*r They should be clean cur and 

times applied ;us a mixture with kerosene.. The mag- upright. If they arc not, the. boh should be replaced, 

pattern arourjd rite crack and shows where it is located, spreadsonr^ttljc a^sr^l^:>o.ndy to be visible torhedyr. 

. * . A i I j i 1 1 ithc'iiutihoiilvf w into che bolt e^ily and with- 

2. Rtpatr. Attempts to repair cracked rods should , < L L . . ' . 

T**^.^, No cliontcs 2^^^^^^ 

shouJd be taken with a defective rod, as serious dam- 
age will result if breakage occurs durnig operation, 

- url — 

is tight pn f hc : -.tteOwcb> xi*m$&ior dirty threap are 
•indict ted , • " The . thread* : of the nut and th< Mt w* u be 

Ci ^osMfui; riUH hij • 
Barren vi oottv 

dirt into the threads, k solvent and. a stuT bridled 

Connccciny rod bolt, are required to ho)d che con- ^li should be used 
leccmsrcdb^m^ (c) Nut uorked loose. Their -should be no need to 

tension on che intake stroke of the four-stroke cycle movcmaU: of , h . c fc y U t hcrc 

b any , the key will 

cn £ ine - jend to wear, ant? possibly fail out, deavinq the nut 

I . Causes a>id prevention . Boks may become defective un P rnreefed : (hec Figure 13-?8^ 
asaresulr of the folkiwmg: 

ft mm : 



or nm. it must be tcpl.*cc4 When cither A foutcv- nut 
or a f.uiltv holt, is fornix!, ii is advisable that both the 
not and bolt be replaced at the same time, frit a good 

A£o$t connecting rods arc equipped >vjth oil pas- 
sages to CQttduct oil from the connecting rod bearing 
to the piston pin W ben th<st passage* become dogged , 

piston, -piscoa pin, and r tng f;aiare& areliketv to result. • ^f^^jjg^^_. 
•:UtrfonuaateW t .there is nn way that mmn pin lubri- v - •^^■B 


cause. If the trouble can be attributed to one of the 
above, the necessary correction must be made and the 
bore again checked. If permanent deformation has 
taken place, it will be necessary to replace the rod. 


1 3E1 . Crossheads. As stated at the beginning of 
this chapter, most single-acting engines employ trunk 
type pistons. At all points in the stroke, except at top 
and bottom dead center, there is a side thrust exerted, 
first on one side of the liner and then on the other, 
depending upon the position of the piston and the 
connecting rod and the rotation of the crankshaft. 
(See Figure 13-30.) This side thrust, which is moder- 
ate in the smaller single-acting engines, is absorbed by 
the cylinder walls (liner). The presence of this thrust 
makes an oil film necessary between the cylinder and 
piston. This film will prevent metal-to-metal contact. 
If the clearance between the piston and cylinder is 
excessive, a pounding noise, called piston slap, will 
occur as the thrust alternates from side to side. 

An entirely different situation arises in double- 
acting engines as a result of the forces of combustion 
acting on both ends of the piston. A piston rod must 
be used in such an engine to permit the use of a stuffing 

box to seal the lower cylinder. The connecting link 
between the piston rod and connecting rod, known as 
the crosshcad assembly, absorbs the side thrust normally 
taken by the cylinder liners. This assembly, therefore, 
guides the piston rod along the vertical axis of the 
cylinder (see Figure 13-31). The crosshead is the 
head or block that slides along a guide, commonly 
called a crosshead guide. 

In Figure 13-31B, gas pressure exerts a force that 
moves the piston toward the crank. As the engine is 
rotating clockwise, a compressive force is exerted 
upon the connecting rod that not only tends to com- 
press the piston rod, but also tends to push the bottom 
of the piston rod to the left. This tendency to push 
creates a side thrust that is exerted upon the machined 
steel surface of the crosshead guide, through the cross- 
head. In A of this illustration, both the piston rod 
and the connecting rod are in tension, with a resultant 
thrust again to the left on the crosshcad guide. Thus, 
for a double-acting engine rotating in the ahead direc- 
tion there will always be a side thrust exerted against 
the crosshead guide. This is unlike the side thrust in 
a single-acting engine, which alternates from side to 
side. For double-acting engines, the side thrust acts in only 
one direction, for the ahead direction of rotation. If the 




Digitized by 


Figm 11-30. Singh-acting •ngin: 


i\lhHWh,n) ki ehc H a id H ion Jrutbie- acting cw^nc p ^ xny rH< xtv$**Kid< *a*i <owi£itfug-xvd drably:, 
absorbs Ihc >,dc rhrusr whea die engine, is ^rnmg m lif , Hamilton HOS engine. This ,ssemb!y is nor 

turcrs ro rtrson ro crosshc.tds m ■. 'most erf the larger the yame. 


head, "slides be rwten the crosshead guide and the crosy 
head gmde gife as the engine opttucr-. The cross head 

tight fit with ih£ main housjrtp, wink the crosshead 

13-34.) -Thus, the side thrust in the ahead dircetio rt of 
rotation is exerted upon the £ro$$bcad guide, 
the astern d-—— - - ^ >~ - 
ginde gibs. 

The connection her svecn ths piston rod and cro^~ ^< 

being a spherical' bronze not scre\v.jpg on the threaded C * K * 1 ' 
end of the piston rod, die socket Win 

from tiu'nn-rg on the, : piston rod. Ttic purpose -^nrk^r >sS(errvhk' 'is- rirt- eb'mi^nsa^ for ' 

imiczhl on thc sute.oetbe,cvosshc^ slipper. It is slipper jHidgutfe. 

probable that chc cn.ft»t w.ll ce;se .pnttng. When The flow of this lubricant must not be stopped, or 

excessive clearance between the connecting rod the babbitt or? the dipper will rack, increasing the 

anee/iiis imprntivc that the tn&tw be babbitt wUmm bcftitoxog rtiCicoJ 'or pitted. Nick< 
secure^immediaMv upon an? and every indication of ing or pitting is also ireqtjefcik the result of improper 
' impending trouble. The trouble ir * ; ^ , ; , . . 

rhoan^hiv and any rep.r- 
Excessive ball-and-soc 



within rhesocker will alter tins durance. The ;i|}dw-. alertness of the watch sunders. The asm! damage is 

able clearance is between O.OOVm. and 0/008 nr. This limited co n mined bushing o? crosshead piiu In many, 

clearance can be changed by altering the thickness of cases, however, the dowel that prevents the dross head 

.iSteeUh^n ^united between the socket and die cover pin from rotating in the : connecting rod *ork has 

nut. If the clearance exceeds the prescribed maximum sheared allowing taxation of the crosshead pin. This 

(a) Lack: of lubrication 

added beneath the scsee! shim ig increase this clearance. 

i surface grinder or anv other suitable .device. A sur- 
face plate used in conjunction with a Pru?s 
coating will give a good mdkadon if an eye 

metal has been removed tf the deaf anc* * too small, ™ " 4 — ; . 

. Lx .v, cu . , 00 improper taring of crosshead pm ro cmss- 

the pjsroti pr^aWy will not .rotate. Sbws must top fed piirfebin^ 

k this clearance. . ^ . t ^ s . U V 

^a;) Z^rcft 0/ tubftcatton, An adequate supply of Inbt l- 

be contiti^iJy supplied to the bushings to 
mer^co-metal contact which would result m 
of & hm&wgB, As overheating iXffurs, the 
crosshead covet nut. crosshead pin w ill expand, sei zing agatet its Nshity;. 

The spherical nut should he checked at the piston As stated Above, frozen bushings wtlf endanger the 
overhauls. In installing a spherical nut. special care cooling o*J flow to the puton t leading to piston over- 

to receive the dowel The manufacturer has inscribed Oce Figure 15-371 
the word c a 1ft bon above the threads on the pitcon tod' 

remove the dowel during disassembly . 

The haiJ-and*ack« clearance should be checked 
whenever excessive clearance as indicated by a distinct 
knowing or pounding noise during operation: The 


iog or knocking is evident. 

— _ . — -., - 


The external symptoms- of a seized bushing and pin 
vary, depend m£ upon zkc extart of the trouble. The 
most pm/nincnt sympioavis high local heat ac the 
unit with improper clearance. Smoke may be evident 

Fwr* mm 


in rhe vicinity of the umt. The engine may fail 
stieed and power if one or m-ore stnits sei^c.;' Bxo 

vibration and metallic noises are hoc um^aaJ* If the 
bushings freeze to the pin, there isdaugc/ of the/bush- 

gtnue, tnis conncc- 
tion k stationary. The other fiqfc is connected ro rhe 
bolkw crosshead pin. giving a ilexiMe ctmnection 


be properly installed so that there will be an unob- 
structed oil passageway through the linkage assembly. 
The link pin must be stamped or marked to insure 
proper installation. During any disassembly of the 
crosshead assembly, the oil passageways must be 
inspected and cleaned if necessary. 

(b) Improper fitting of crosshead pin to crosshead pin 
bushing. The correct procedure in installing a cross- 
head pin bushing is to hand scrape the bushing, after 
it is pressed into the crosshead, to establish properly 
the designed clearance. If the bushing is improperly 
fitted with insufficient clearance, there is danger that 
immediately upon starting, the crosshead pin will 
expand as a result of the heat liberated, and seize 
against the crosshead pin bushing. If the crosshead 
pin bushing clearance is excessive, there is the proba- 
bility that a pounding noise will emanate during oper- 
ation. This noise is similar to the noise resulting from 
wiped connecting rod bearings. 

2. Repair. In removing a pin from the connecting 
rod, a screw type puller is used. It screws into internal 
threads within the bore of the crosshead pin. 

If seizure has occurred, a new bushing and probably 
a new crosshead pin should be installed. The cross- 
head pin must be fitted to crosshead pin bushing cor- 
rectly, as stated above. 

In replacing a crosshead pin, the nuts at each end of 
the pin should be alternately taken up a little at a 
time until each is secure, before they are locked with 
a wire. 

If the dowel pin securing the crosshead pin to the 
connecting rod has sheared, it is likely that the con- 
necting rod will also be scored, as previously stated. 
In such cases, replacement of the connecting rod is 

c. possible trouble: 


The bearing surfaces of the slipper are babbitted. 

1. Causes and prevention. The outstanding causes for 
the failure of the babbitt material arc: 

(a) Improper lubrication. 

(b) Careless handling during overhaul. 

(c) Misalignment. 

(a) Improper lubrication. The means by which the 
guide, gib, and slipper receive lubrication has been 
discussed in (b) Misalignment, page 262. 

This lubricant must not only be of sufficient quan- 
tity to prevent metal-to-metal contact, but must also 
be free from water, acid, or foreign particles for the 
prevention of corroded or pitted surfaces. 

Digitized by G(X '2^ ' 

(b) Careless handling. It is extremely easy to damage 
the babbitted slipper during removal of the crosshead 
and connecting rod. The slipper must be immediately 
covered with a soft, clean cloth for protection against 
scratches, etc. The slipper should be placed in such a 
position that the babbitted surfaces do not come in 
contact with any metal surface. In one method of 
removal (discussed under 2. Repair, below), the slipper 
must be momentarily rested against the hand-scraped 
housing surface, but extreme care should be exercised 
to see that a large soft cloth is placed between the 
contact surfaces. The guide and gibs must also be 
handled carefully. 

(c) Misalignment. Any misalignment that will cause 
undue wear of the surfaces will result in wiping or 
melting of the babbitt on the slipper. 

2. Repair. When maximum clearance limits arc 
reached, the worn guide, gib, or crosshead slipper 
must be replaced by new parts furnished as spares. 

There are two methods for removing the crosshead 
slipper assembly from the engine. In both cases, the 
connecting rod and crosshead are removed together, 
as a unit. In one method, the guide and gibs are also 
removed as a unit. In the other, the gibs are removed 
from the guide, the guide being left in its normal posi- 
tion connected to the engine frame. If it is necessary 
to remove the guide, in this second method, it can be 
done after the crosshead and connecting rod assembly 
is clear of the engine. 

There are several advantages for the method of 
removing the guide and gibs as a unit. It makes the 
lower cylinder head hold-down nuts more accessible 
for removal. It also decreases the possibility of drop- 
ping or scratching the babbitted surfaces of the guide 
and gib when they are removed from the engine sepa- 
rately. The gibs are secured to the guide by fitted bolts 
that must be driven out before the gibs can be removed, 
if the second method of removal is used. Although a 
brass rod is recommended for driving the bolts, the 
threads still become bruised and it is almost always 
necessary to run a die over the threads of the bolts 
before the bolts can be used again. The only disadvan- 
tage in this method of removing the guide and gibs as 
a unit is the necessity of resting the slipper momentarily 
upon the hand-scraped surface immediately after the 
guide and gibs have been slid from the slipper. There 
must be a large clean cloth between the contact sur- 
faces to protect the relatively soft babbitt material. 
This support for the slipper and connecting rod is only 
momentary, as stated, until the crosshead assembly 
can be hand supported in order that the slipper will 
not contact metal surfaces while the engine is jacked 

Origiral from 

2 1 

A injpftnj vvhicit I 
^ pressure the rod. The correct vertical cltar- 

^ . -tncfe between the stuffing .box rmgs is obtained by 

^ mean, of. spacer rjogg located between each of the six 

a is cooled, 

*. to pre-vtnt overheating, by oil piped from ch« pwon 

•unt of lubricant carried by the rod to the euoJin*mi header. Tlu, *i passes mtu a prove ui the 
' is regulated by the oil scraper rings in the bottom of the stujfi&g box, dtvkleJ by wo >v ti).s to 


- 05 

nor remm vmia*f, excessive pressure between the 
stuffing box rings and ooe side of the rod will result in 


be maintained at all times. See (b) Misalignment, 
page 262. 

(e) Careless handling by inexperienced personnel. Many 
piston rod scratches have occurred because of careless 
handling during removal and installation. Bent, 
scratched, or dented rods may cause scoring. If care is 
exerted in installing and removing the piston and rod, 
many subsequent troubles will be avoided. 

2. Repair. The engine instruction manual gives 
.008 in. as the maximum distortion allowable before 
rod replacement is necessary. This measurement can 
be taken, after piston disassembly, by supporting the 
rod between two accurate V-blocks and checking the 
bow reading with a dial indicator. 

The stuffing box must be handled carefully to avoid 
rod scoring. It is advisable, during piston removal, to 
check the rings in the stuffing box for free movement 
and play. If the lower cylinder head has been removed 
and the stuffing box is suspected to be carboned con- 
siderably, it is advisable to soak the entire stuffing box 
assembly in a container of clean diesel fuel or Gunk. 
The carbon will be softened and can easily be removed 
after several hours of soaking. The assembly should 
be secured by two pieces of locking wire to prevent its 
coming apart during the inspection and soaking period. 
One wire should extend around the periphery; the 
other should extend through the passage usually 
occupied by the piston rod and around the outside 
snap rings. The stuffing box should not be disassembled 
unless absolutely necessary. If necessary, the old fire 
rings should be replaced with new ones. The fire-ring- 
to-rod clearance should be from 0.001 in. to 0.0015 in. 
The stuffing boxes should not be switched between the 
cylinders nor should the rings be interchanged. 

The precautions given for the stuffing box apply also 
to the division cover. During the overhauling of the 
piston, the division cover should be cleaned, butt 
clearances taken, and the rings overhauled if neces- 
sary. The division cover will not be subjected to the 
high temperatures and pressures of combustion; there- 
fore, less troubles will be encountered with the divi- 
sion cover than with the stuffing box. 

If a new piston rod or stuffing box has been installed, 
there should be a wearing-in period of operation. The 
procedure of operation may be obtained from the en- 
gine instruction manual, and it should be followed 

exactly. Under no condition should the lower fuel 
pumps be cut in when operating with a new rod or 
stuffing box. This will prevent any possible rod seizure 
within the stuffing box. The lower cylinder indicator 
cocks should be opened quite often during the wear- 
ing-in period, to remove excessive lube oil and fuel 
oil accumulations. 

b. Possible trouble: 
broken, shattered, bent, or seized piston rod 

If a rod becomes seized within a stuffing box, an ex- 
treme load is applied to the moving mechanisms, often 
bending or breaking the rod and the stuffing box. The 
trouble will be evidenced by a severe noise from the 
cylinder in question and often the engine will stop 
suddenly. Breakage of the piston rod usually occurs 
either near the shoulder on which the lower piston 
head screws, or at the lower end of the rod where the 
spherical nut is screwed on. 

1. Causes and prevention. The principal causes for the 
above difficulties experienced by piston rods arc: 

(a) Spherical nut failure. 

(b) Carboned stuffing box. 

(c) Crosshead misalignment. 

(d) Wiping of connecting rod bearings. 

(a) Spherical nut failure. In several cases, the spheri- 
cal nut has broken loose from the piston rod, bending 
the piston rod and connecting rod, ruining the con- 
necting rod bearings, and breaking the division cover. 
It often results in shattering of the lower end of the 
piston rod. (See (c) Spherical nut failure, page 262.) 

(b) Carboned stuffing box. See (b) Excessive lubrica- 
tion of stuffing box rings, page 265, and (c) Improper 
cooling of stuffing box, page 266. 

(c) Crosshead misalignment. Excessive crosshead 
slipper clearances can cause crosshead misalignment, 
resulting in a broken piston rod. 

(d) Wiping of connecting rod bearings. See (a) Wiping 
of connecting rod bearing, page 262. 

2. Repair. There is no repair for a bent, broken or 
shattered piston rod. A new one must be installed and 
the cause for the failure must be ascertained and cor- 
rected before the engine is operated again. The correct 
procedure for wearing-in a new piston rod, as described 
in 2. Repair, above, must be followed. 

Digitized by GOOSlC 267 



Digitized by VjOUyiC ^ 


.- .--S I'' > 


-v- V- 

^A'v : : : •: 

muse tnorougmy inspect inc. cranKsnair uunug everv age ro t he connecting rod and -piston assemble 

bearing removal and installation, whether the over- L ln coc>ciCcnon with the proper posir/oainV of rhc 

ruui u due to an tmexgenev te*rdcma or a pan; diht uppc r and lower shdb ? i it mu*t also be remembered 

progressive maintenance process. t w used tear mes must bs reinstalled in dictr correct 

sstve maintenance process- t&a* used bearings must be reinstalled in dicir correct 

The importance of correct bearing installation can- Jocation- (cylinder number). If .not. damage mav be 
00r be ovci cmphas^ed. ^Not only will , incorrect infl ^ tcd upot5 thej^rnafc When the engine s operated. 

may also rc- Forfth^ safety of the crankshaft, *t is- imperative so 
e Allure or maintain proper \u bnca d ng m ? .temperaiur<» and pre*- 
•• ;: ^ - ->he 'at! reaches an excels] ,ve temperature, 
crverheuurrg may mem alonir •.v«ch failure 
w.w*..>..vf ,„;n ^.k^u 

occur also Therefore, if is evident that the proper 
feature of the lubricating oil most be maintained, 
The oil pressure must also be sufficiently high to pn> 

"To prevent damage to the shaft, the preventive 
measures that arc mentioned in Chapter I*> muse be 
followed exactly 

(b) Improper and careless havdlw^ during overhaul. 


In some of the larger engines, special tools are pro- 
vided to aid in removing the main bearing shells. The 
improper use of these tools may also scar the shaft. 

It is relatively easy for operating personnel to strike 
the connecting rod bolts against the journal surfaces 
during the removal and installation of the connecting 
rod assembly. Every precaution must be exerted to 
avoid such an occurrence. The instructions set forth 
in the engine instruction manual for the removal and 
the installation of the connecting rod assembly (rod, 
bearings, lower cap) and the crankshaft and main 
bearing assemblies, must be followed if crankshaft 
trouble is to be avoided. 

Some means must be provided for the protection of 
all journal surfaces after the bearings have been re- 
moved. Leather belting is very satisfactory for this purpose, 
also clean cloths. However, under no circumstances should 
waste be used. Some engines are so constructed that a 
light clean board may be placed in a position to catch 
all falling parts, tools, or other objects before they 
strike the journals. One manufacturer recommends 
the use of a flat shield of sheet metal, wood, or fibre to 
protect the main bearing journals when the main 
bearing cap is removed during the overhaul period. 
The shield is held in place by the main bearing studs. 

(c) Abrasives in lube oil system. Dirt or metallic par- 
ticles that enter the lube oil system will score a journal 
as well as damage the bearings. (See Chapter 15, 
pages 284 to 286.) 

2. Repair. Whether a scored journal can be properly 
repaired or not depends upon the extent of the scoring. 
If a crankshaft has been overheated, the effect of the 
heat treatment will have been destroyed and replace- 
ment of the crankshaft will be advisable. 

If the journal is scored to a slight extent, an oil 
stone can be used for dressing purposes, provided that 
certain precautionary measures are observed during 
the procedure. These precautions, stated below, must 
be followed to prevent further damage to the shaft and 
to the entire engine. It is advisable to have all oil 
passages within the journal, and those communicating 
between the main bearing journal and the adjacent 
crank pin, plugged during the dressing operation. 
Wooden plugs should be used for this plugging, which 
prevents metal particles from entering into the pas- 
sages. If the journals are dressed with the crankshaft 
in the engine, metal and abrasive particles must be 
prevented from dropping into the sump and entering 
the lubricating oil system. A clean strip of canvas, or 
cloth, or a piece of gasket material may be placed 
below the journals for this purpose. 

After dressing, the journals must always be washed 

with a good cleaning solvent, such as kerosene or 
diesel fuel. This procedure must include washing of 
the internal oil passages as well as the outside journal 
surfaces. Some passages are large enough to accom- 
modate a brush to assist in cleaning. Other passages, 
while not large enough to accommodate a brush, may 
be cleaned by blowing out with compressed air. The 
passages must always be dried by blowing with com- 
pressed air. 

In the dressing procedure a fine oil stone, followed 
by finishing with crocus cloth, should be used to 
polish the surface. 

Some manufacturers have recently experimented 
with the salvaging of scored crankshafts. The journals 
have been undercut and then built up by chromium 
plating or metal spraying. They arc then finished to 
the original size. 

Extensive tests are being performed to determine the 
suitability and reliability of chromium plated journals 
for the prevention of wear and scoring of the 
journals. The process of chromium plating crank- 
shaft journals is now performed by industrial shops 
specializing in journal plating. 

Other manufacturers recommend reconditioning 
scored journals by grinding the journals undersize and 
installing undersize bearing shells. However, this can 
be done only by the most experienced personnel, thor- 
oughly trained in that procedure. The necessary 
crankshaft grinding equipment must be available if 
journals are to be ground. There is a limit to the 
amount a journal may be ground. If the journals are 
damaged beyond this limit, the crankshaft must be 
replaced. This procedure, however, is not encouraged 
by the Bureau of Ships. As a rule, a new or recondi- 
tioned crankshaft should be installed to eliminate the 
necessity of carrying a variety of spare bearing shells. 

Never stow a crankshaft on any metal surface. If a shaft 
is to be removed from the engine, it should be placed 
on a wooden plank with all journal surfaces protected 
by leather belting or clean cloths. If the shaft is to be 
exposed for some time, it is well to protect each jour- 
nal surface with a coating of heavy grease. 

b. possible trouble: 
broken or bent crankshafts 

The indications by which a broken crankshaft may 
be detected depend upon the extent of the break. A 
crankshaft break may be only a slight crack in the 
web, pin, or main journal. If so, the engine will not 
cease operating as it would if the shaft were completely 
broken. Figure 14 4 shows a cracked main journal. 
Detection of the crack was made possible by the use of 

Digitized by GOOOle ^ 


j or a severe sttucldering 
be SSn.Hoiicaaon of & broken crankshaft. If failure of 

(K) Excessive bearing clearances, 

< l. ' for further %md)'> 
In certain engines., these critical speeds fait vmhlo 
the norm*! opera on,- ru»ge. « so, the m«» Sec ' L T «f air : 27L iof PTCcaui.oriar.V natures 
manual for that m*ttr.«itl stare thai &e engine • , £0 ^observed by >per*erqg pmonnd -during crank- 
should norbeoperamJ for anr-Wh of rmie wuhirt shatr Overhaul, .rtspecr.o*. and «rv»an g . 

C rankshaft servicing consists not only of an inspec- 

mmsatj ro pass thfo H b the enncal ran $f> ft nock W ""^"^^™ P^'?^ ti , . : £ . 
jprt*«W«uft to pas* thr«*& h-aswtcklrts-pvssibU, Some maiiafacwiers icquire. that defection rcad.Bgs 
,-r-, V . i u to" r u . "' . ■.•:«-■■> a he takefl at each cr link at everv pe^ocitcovcfhatil De- 

(f) f*fip<i failm (See Chapter 15, page '282..) 

t _ 1. C. . - »1 1 ... iLil I ....... ..i . _ _ I fv >-;... _•' TL'.^ 

at every pcftocfrc overhaul" 
flections are aiso taken in aligning m engine and 

crankshaft More t hi'.s 

Fatigue failures are also aggravated by the presence 
of torsional vibration (Figure 14-?). The surface of 
fracture A is approximately at a right angle* to the 
crack designated }l in the illustration. Thi* is indica- 
tive of torsional vjbrarioiL Cracks due to .fatigue 

micrometer employed to 
the distance- between adjacent 

.* yV.Vi-. -.'i . rati] ftlWW vs- ! ! •• •'. ■'->■- '. . •»: ► 


. •• • 


P«?» and a center punch or prick-punch must be «IKDE^ 
used. The engine instruction manual should be con- • 

sutted (otAht prvrcr location of new mark*. , r r;^ lifiiiSR '.\ 

Readings usually are taken at the folk wing crank 
fraitiofi*:. top deadi center, inboard, near ot at bottom 
dead center, and outboard In some engines, it is pos- 
sible to take readings at bottom dead center In others, 
the connecting rod may interfere, making it necessary 
r.o rake the reading as near bottom dead center as pos- 
sible wKhour having rhe gage cotaste fco.ntef* mih r : /^(^BT^ / 
the connecting rod. The engine inscrucripq manual 
will contain informadon concerning the prop* 
rion *>f rtrc crank when readings are ro he taken, 
the gage is in its lowest position, its dial will bt up~ Figvr* Crankshaft bridge gag: 

side down, ncccssixwng the use a minor w& ftash- 

light co phtam a reading 

bearing wear has orcurrcd. Some engine roanufac- 

hydraulic coupling In aligning an engine and genera 
tor, the ir^t^Jatio^ of new chucks between the gener- 
ator and i^.h^se mify be necessary to bring cbe dellei.- 
tion within the allowable value. U ma? also be 
necessary to r sb»n the generator homonraUv to obtain 
proper alignment. In ahgmng an eugiric and i hy- 
draulic coupling, the couphhg must: first be correct! v 
aligned with the propeller shaft and then the engine 
properly a hgncd to. the coiipling. rather '.nan chc 
coupJing ro the, cosine 

A cr^nfohah Kr/dge gage (f j gurt. 14-9) uj furnished 
with several rv pes of engines to check the Wear of the 
mam bearing .shells, it is placed on the crankshaft, as 
shown, and the clearance between the; bridge gage and 


„_,oyablc cam sers. The cam 

auiv ^yi , v*vm awiww m ftVVPM IV lily MJUUi 4XLU JUCKCU 

1481. General Moss o* che engine* lo «*c wd«y io p,,^ H ,' scfew 
emplov forged alloy steel jhafe. carrfully h«r m»cerf ' Another wguw- in use employ* two- ? We adjust- 
and surface hardened,: Mo S i-,ot. these shahs *« one- ^ ^ . d d M the shitft< for changing fuel 

< - • 14-15). : ; . 

, ■ sr'* v v->"..'";, . ■ 

crack* such a.$ that shown iu the Illustration, may or 
may not cause failure of the cam. However; the pres- 
ence c>F such a -crack ou c he cam surface is^nsjclercd 

s uOk ten t py cJimr; prem* rare bt**kdownof that sur - 

More oft™, 'however, the damage may be g*Ufcig< 
Figur* 14-15.- Camshaft wiih *d stable h,ei pump t ams, sc&riag, or excessive wear or the cam surfaces. The 

. mm 

*wm mm 


oor only for the proper operation of *ke engine bur 
aisc^to prevent possibly damage to the crvgme parts. 
The t;tlve opting Jcnk^,ihc?^d be msptctcd frc, 
duenrlv during QC^arion td cla^rmuic if j 

^ ..-V..- • •>::,.- •■ 

lV broken, chipped or improper I v seated, valve springs; are damaged. Figure 14-18 shows the method of rc- 

inspecting push rod springs; inspecting' push rod end moving an indi vidual cam from its shaft. The securing 

joints for propci- spring- and inspecting cam follower key must be dnveii our. This is usually accomplished 

surfaces lot grooves or scaring-.. with the aid or a Lev dnfr. 

(c) Faitunnf cimsijft fjar..: The sudden failure of the The camshaft must be cleaned thoroughly during 
camshaft gear may cause considerable damage to the evWy Overhaul in which it h removed from the: ; en- 
cams as well as damage the entire valve operating gine: The shaft shown in Figure' 14 14 is m heed of a 
linkage. Broken or bent push rod:, may occur as well thorough cleaning. Kerosene or dtesc! fuel may; be 
as valve damage caused by conua with the piston ' ■ used After washing, the shaft should be dried, by 

vcotivc measured to minimize gear failure and ihprefav When installing and removing a camshaft through 
reduce cam casualties resulting .tram such failure the top of the camshaft pocket as shown in Figure 14- 

(d) Wmi eaf* w&rir Worn rollers will cause scoring, 1?, extreme care must he exerted to prevent the )mr* 

page 275 

2. Repair. A shaft with scored or broken cams 
be replaced. If the cams are of the individual > 

ams mast 
aai type, 

they may be removed separately and replaced indi- 

easily, ana thereby reduces the possibility of damage 

to the cam lobes and to the bearings. 

— — - — i — — i — 



the hearings show scoring, or **re worn to such an ex- 

Digitized by 



1 5 A1 . Introduction. Bearings become a continual 
source of trouble unless personnel entrusted with 
the operation of the engine follow exactly the 
recommended practices in operation and maintenance. 
Bearing failures are extremely serious, since with the 
increase in production of diesel engines, a critical 
shortage of spare parts has been created, particularly 
main and connecting rod journal bearing inserts. The 
loads which these bearings must withstand have in- 
creased with the increase in rating attained by higher 
engine speeds, and increased bmep (brake mean effec- 
tive pressure) in high-speed lightweight engines now 
in general use within the Navy. It is not uncommon 
to find piston pins subjected to loads of 6000 psi, con- 
necting rod bearings to 3000 psi, and main bearings to 
1500 psi. These new changes create problems which 
demand more attention to intelligent operation and 
the practice of progressive maintenance. 

Before analyzing troubles encountered with journal 
bearings, it is well to consider the types of materials 
used for bearing inserts. At present, the bearings 
most commonly used in marine diesel engines are re- 
ferred to as: 

1. Bronze-back Satco and steel -back Satco. 

2. Tri-metal. 

3. Copper-lead. 

1. Bronze-back Satco bearings consist of a bronze back 
bonded with a high lead content bearing material. 
The physical and chemical properties of the bronze 
back meet specifications that are based on the type 
of bearing and the service for which it is intended. 
The bearing material, known as Satco, is primarily 
lead (98 percent) and tin (1 percent), and varies in 
thickness from 0.015 inch to 0.045 inch, depending 
upon the service for which it is intended. 

2. Tri-metal bearings consist of a steel back, bonded 
with an intermediate layer of bronze approximately 

Digitized by GQoQIC 

0.035 inches thick, to which is bonded a layer of bear- 
ing material 0.003 to 0.009 inches thick. The bearing 
material is either lead base babbitt (usually 80 percent 
lead, 5 percent tin) or tin base babbitt (usually 88 
percent tin, 8 percent antimony). 

3. Copper-lead bearings may consist of a layer of 
copper-lead bonded to a steel back, or merely a 
copper-lead shell. The surface may be plated with 
0.0015 to 0.0020 inches of tin-lead or flashed with 
indium. In either case, the copper-lead is considered 
the bearing material, with the tin-lead or indium 
plate serving primarily as a protective coating against 
corrosion. Since copper-lead bearings are relatively 
hard, a harder crankshaft must be used in conjunction 
with them. 

To understand more fully the causes for journal 
bearing failures, the loads which each bearing must 
withstand during operation should be considered. 
All journal bearings are not subjected to the same 
manner of loading. 

In the two-stroke cycle engine, the compressive and 
expansive forces are greater than the inertia forces 
set up by the reciprocating parts. This is due to the 
fact that for each cylinder a power stroke occurs 
with every revolution of the crankshaft. This causes 
a load to be placed always on the lower half of the 
main bearings, lower half of the piston pin bearings 
in the connecting rod, but upon the upper half of the 
connecting rod bearings. 

In the four-stroke cycle engine, large inertia forces 
are imposed during the intake and exhaust strokes. 
These forces tend to lift the crankshaft in its bearings. 
This results in a reversal of pressure, causing the load 
to be applied first on one half and then upon the other 
half of the bearings. 

Of course, in double-acting engines, there is a 
definite reversal of pressure in the bearings. 

Original from 

a. fomxt.1. troubie; ~~ " , ths danger i>f begins fjiiwe of the dcid cylinders 

dences of corrosion, 

No attempt wiirht made to diifcrcotbte between 
the troubles encountered with main bearings and 
etaefcrpto (conoecrmg rod) hstfnn£s r as ths causes for 

(d) Abrasives in lubricating pit 
(V) Irtadequate supply of iubnesv-mg oil. 
(() Exmisbft of boring shdh 

(g) Fadfy ifist.-UJar.ton. ^ 
Cb) Inarreattoo to recommended operation. 
»* ransrs while ntif srinrnrnrnon. that baivie often 



high localized pressures and temperature* ratsr Figure isrics w * t«„ ^^^.^ 

15 3 ..F., " r ^L* ^ corrostorj K and on S^itco e^s* •<*•*'> : y,^ ^ & • > ^v,** * r i*-**. • j* 
- material IhtS condition occurred over ap- : > V - .v 

proximately 50 percent of the bearing area during the T^^^S^ESB^^SB^^^ 
first 24 hours of operation. A similar xanduion is ^^BwHTOfB^WS^^B 
•shown in figure 3 5-4. w h.ere the. corrosion ' is due to ; - J\\ v 

- ' • . 


and retnpemum 'exist m the lower half of the bear- ^ 
ing The corroded area^l^ &i^r^ ^ * * 

cent of the lower sheh. The minute p.ts repecsem > - . ' ./v 

apprt>xututely 50 percent of fftfcb&riiig surface in the 
area the pits art so dc*eJy spaced that, they form 

channels, the oi! film is not continuous and the load ^ MAGHir , 

carrying area of tht bearing rs reduced below the 

point af safe operation Tbis bearing has been in 
operation for 284$ hours; the corrpsu>n developed in 

Uti-iG hours. 

Corrosion in the cadrmur^ 

and was accelerated by the presence of foreign m 



bearing ?i himm I led. 


■ Th&.&m&ztite diar atta&k eadmiyin bearings will 

but in a somewhat 

fiflff* J5-3. fo«or« efue fo eorratmn 


different manner. The cadmium alloys usually con- 

i'flgs, the metals are nut combined - and small particles 
of lead are frozen into the nuns vf copper. Figure iy 
6(A) Shows a corroded copper dead bearing 'ununi- 
fied) . A • eross-aec c i on of fhp i.&im£ surface is shown in 
Figure j><0} The lead at the affected surface of the | 
bearing has been -Vira^ed bv the organic acids formed 

.i. ^ • . • - i . i I ■■ . .. , i 

in the bah converting it iota a lead-soap compound. 
This compound is then washed away leaving. 4 porous 
ennTv»r 5turf:>r^ whu-h ( fUinr^trr:iti-< 

•i lcad-so*p compound. . y"'.;, .. 

.1 ! ... • .......... *V ■•, 

» 4 -.v\ h tip ♦ - ;f • • ^ • v : - »5 



. — — - -Al 


figor* ; femg fo,7</re d«# fo mac/#goc** W pressure 


f articles without d^nuge/ TIk: particle is cmbqAdcJL \ 

BACK 'MeuHic famctes embedded >« ? a Irr-nwwl bewmg are 

POOR BOND BACK : : ,ho^ (magn^dV.nB^urc 15 9 

MAGNIFIED 75 T^ES Tfa surface of a coptvr-le.J bearn lff is rdan*dy 



" .'.V 

figure 7 5-10 

0, Dtfmcfl** bond b*tw*»n bnnze ond M 0/ o Tri -)»•*«/ fceorm*. 

potiiug purposes. ^ 1 torture, \t is m vc chat jji 

iourn-j< bearing surf arc ,u all tunes Junng operation. 
The »oufn.ti, muvuig within* ics hcurrngs, musr be' 

• -tO'inetaJ contact vvi.H release sufficient jneir t<i 
melt rte .v:}ftcr of the materiiik, -of th^ two surfaced 
Tht wktt ma^ai m this case i.s At babbitt and not 
the lOurniil Most babbitts used in cngiats have Lurh 

, v , • fa. 

or -waste must not 

internal '.parts. Sec (h) liiatreftriah to recommended rornon of the shell and failure of the beanug 
:ion/page.2iCro obtain coerce npcranonaf pro-;, 

vytcb resect to ore of Jubr^ttin^oiL ' / - jgMj^^ • 

of htanng ML if the pil .groove" is jaBR^C ^-'v::: ; ^j^g . 

oed i'n the rod, some support for the bearoig -^'sBBHm''^ '* ^'-^^^' ' '^^^^^^^k 

machined in rbe jod. some support for die bearoig 
shell is lost To. isUch ca^, under the extreme loads 
to wb'jcb-chi; bearing- iff mb^cted. the she!} extrudes 
i&to the ml groove, .This is particuiarl v true of bronze 
back .bearings. The degree of extrusion varies with 
the hardness cf the bronze shell. The result of this is 
to isubjecr the edge of the extruded section of the bear- 
ing material to tentorial forces, Numerous cracks 
and pits will eventually result as shown In Figure 

The extruded, area does not contribute to the Joad 
carrying area of the beinog but acts rather as an oil 
passage. The result is that rficM of the oil will flow 
around the bearing m the groove. Consequently, this 
oil performs very pooriy as a coolant, and forms an 
insufficient oil film to separate the journal from the 

(g) F«ult? wwlttnon. Assembly errors occur from 
time to rime md nre usually, caused by negligence or 
lack of c^x^ence, Th* most common failures,; ■ iS-f*. & 

>:iu\~'-\tA\iZCv\. )n Urge cnfincs/tbv v<^i<«ic of the 


: • V'' H 

mcnt of main bearings can be caused by a bowed, 
warped or sprung 'crankshaft. This imposes heavy and 




*W ?5~J5. 'tar** mth ^mtr *» co m feW oft*r par/ of IjW^V^^^fffM 



MmuK pus aftd raised surfaces nwy be smoothed by 
the use crocus doth or a bearing scraping topi. After 
:my work tea performed on bearmgi, every effort 
must be made to msture the cleanliness of che bearing 
surfaces. This aisr> applies to thft : bearing back and to 
the crank .Journal and pin A chin film »f clean Navy 
approved lubricating oil should be- placed upon the 
journals and the bearing surfaces before re install anon 
iv&of the lower and upper belong halve* 

amount of material *: removed (usu^v a tetoon of 7< ic «»" c ^ ^ C 

aOOOl tnch of beting material m oRain i uniform ; y3t ndcr nur 

•r three Upper tad iow^im^Wajrii)^- 
^o^c^Z '^Z^^^i^^ Ua,VCS i0S0 ^ d ° n b linder number two journal ) Yet, 

5. NAVY 


- - j • • §| jj| - : ..,;!,„ 

xf'th** occurs, it' is probable thac ths <togw<r will be fore- add., after tightening-. - Figure-. 1 

extreme h haul if noump6s#Wc, to over by tart*] type uf used : and '.'Figure- <tK 

fi the emi»ne wer< £0 be operated under such 4 condi- -Hailed uu* the emrme. The proper "ciongarn 

rioh; th% ■ fr&Anms :wauid te >cverctv dauwed, pos* obtained rramrhc engine ins cruet ton manual. 

■ - ■*■■■■■ 0 1 ........... - v. • 

btarm^ fosttmt \ upper of 

The connecting rod bearing cap nuts must be pulled . "both nun? and connecting rod. Tbu* nvost always he 

5V24. Figure lS-2$alw shews the correct met nod of 
S'rowifig the bearing shelf while measurements are 
betqs, inHn. The- boring should .)hv.n-s he protecred 
!•• c!e.i.'. clf-rKs.. .t* Shown-, 

■ A .-<*••'>, ft . 



— M l. 


„ SIKI. I ALL Oil ftOLU* 

/ V W •' ' I. 1 : " - 
. . * • • • . v\'< - 1 . v ' « * 

These medtsiitements rn as t be taken at specifkU inter-* 
vajs, usually at every o verba uj They arc Uken to 
establish the amount .of beating w^if . Also, a sufficient 

Digitized by 

Go gle 


Digitized by VjOUyiC ^ 


- -Bore 1 jg» 

. 1 1 v.. , v' 1 ' Jt-Al X 1 7*? 1 fc/> 


Inner O.AMF-TFM , 


r J.._., 

: '; - "•• 

• ■ \ : V\ : 




mm Wmft$ 

. • ;r.t: .>.-. : - ;■' • 



A needle beating, rather than a joufnaJ bearing, is 

16-5), due co the difficulcv tt" coawesiuihg .x Mm of 
P lubricant in an oscillatm* journal of thi* type. No 

separator is used, hinte great care is necessary' when 
working with this rype of bearing Note that the 
piston pin serves as the inner rare ofrbis bear .ug. The 
: ptn shown in place is an arbor used tot assewbly . 


figurtt J*-3f. Contesting rod i»e«tft* i*Bo<vi 

bearfcg when u is inspected. A bearing should never 
be discarded' until it has been established that some- 
thing in «dd<tioo to dirt has cursed the trouble. To 
eliminate this possibility, the bearing should bcclcaoed 


Gr#os« grooves 

Loathor or composition 
— flango typo 


Cork disk 

it is turned. Furthermore, it is not necessary that 
these substances be harder than the bearing parts to 
cause indentation of the balls or rollers and races. 
Obstructive materials consist mainly of metal chips of 
brass, steel, copper, or iron. 

(3) Clogging substances. Cheap greases or graphitic 
lubricants will deposit an appreciable amount of solid 
matter in the bearing between the rollers and separa- 
tors. This matter will interfere with both the smooth 
operation and lubrication of the bearing. 

1. Causes and prevention. Bearings become dirty as a 
result of : 

(a) Improper handling or storage. 

(b) Use of dirty or improper lubricant. 

(c) Failure to clean housing. 

(d) Poor condition of seal. 

(a) Improper handling or storage. A bearing should 
never be removed until a clean working space is pro- 
vided. Figure 16-4 shows an ideal working space and 
a definitely improper working space. 

Note that a dirt-free bench, clean tools, and proper 
tools, arc necessary. Note also, that the bearings arc not 
left out in the open. The bearing cannot be kept clean 
in dirty surroundings. Bearings must never be handled 
with moist or dirty hands. They must be cleaned 
carefully as specified under 2. Repair t page 300. 

(b) Use of dirty or improper lubricant. After the bearing 
has been cleaned, it should be lubricated with the 
proper type and quantity of clean lubricant. When' 
grease is supplied in service, it must be made sure that 
the grease fittings, grease cups, etc., are clean. If oil is 
supplied continuously, any and all strainers and filters 
must be maintained in good condition. 

Digitized by 

Go gle 

F G 
Sling f Concontric spring prossvn typm 

Flgvro 76-5. Anti-friction boating soaling dovicos, 



Go gle 

Digitized by VjUU^ 1C ^ 





i *• . ! A • • .L.L....-: i .>,L. 1> .llU .1>,A.J 

pit ■■ 

.... . I 

reasonable care to prevent beading or -improper pasi 

After soaking; the bearing should be slashed around 
fin&.tomzi jh& below the surface of the sof vent. The 

f 7 ) tarr/c P rm*r* ,^/;. h shouidbc made 5hmld ™< hc S P»*> .* bou,d hc rowccd 

certain that .the stuff surface is smooth, and that all ^fticicnrly m insure that all foreign particles are re- 

sharp edges which meht damaae the sc.! elements ~i A short de^ bnsxle brush with bristles that 

have been removed When replug a seal, the *>™ * f r > » h fP fuI L m rcmovm S 

order in : '.Which elements arc ^seM.Wtcf .houid be chip.. Ordinary kmg^bnstle paint 

noted. )f the otderisnotnoted | reference | it* „unu- bn ' sh ^ arc ?»« ^^rmy 

;> . 

; -\., 

fac carer's drawings should be made f ri order to avoid 
improper assembly of the element The scajhfcg dfiS (|f 
raeot and ail rWnioa -u.ouid be thoroughly 

lubricated prior t'o installation. 

. 2.. &eat*H£fas a sh>J>! <>>n both f^&c, // 

* vprchhncara b«*n % and ts m to § |p|| Defective 

bearings of this type musr be sent to, a recond! Hording WM , a 

activity where specjal ^uiprnenr is available for their . 

cJeaniiai? *M bibric^non § ;;< 5 . ^ 

pjny ball or roller bearings must be rho'fodghly " ' " 

fiyu^fi T6-^* CJ«ofii#?g bearing with compressed air. 

should be removed from the working space A bench 

with a smooth, easi'iv cleaned surface should be se- (d) After the .initial cleaning, the bearing is next 
Jccted . All too&to be used must be cleaned thoroughly. immersed jit; the ./Wean of solvent, sloshing and 

I coed All tools to be used must be cleaned thoroughly. 
The bands must also be cleaned and dried. A liberal 
suppiy of clean, liut-frce cloths should be obtained 
and placed within convenienr reach; 

<h} iKt'ltU&t . wo perfectfy clean cans, or other con- 
•tajin^n of Sufficient .'.'sue to accommodate the bearing 

and the workman s hand, should be placed within shmvu <n 
reach, Each can must be (died with clean solvent. iowd lu S 

rotating the; bearing anxil all dirt *s removed, fj^mn^ 
an*i miun^ should ttnrr k dwe if? tin uifne CGrii<met. 

(e) The bearing is then removed from the rinsing . 
can -3nd blovyn. dry with clean, dry. compressed air. 
The beating ramx he hdd.^0ti as 
16 -8".v The. bearing mus* mi beM- 

pirn by force of .or 

This solvent should preferably be clean straight-rua This seep iS a or essentia?, bur u: i> recommended 

used where facibcuts uce available. 

nonUtded ga^oime, Leaded gasoline must not be 
as the lead compound used co increase arm-knock 
properties is toxic. Some individuals are highly sus- 
ceptible to lead poisoning by inb,i',io.M of, or skin 
contact vvith/ leaded ^isoline, When Vu.^n^ gasoline, 
.ali rjecessarv nre preca ut.iOas' must ' 
imeas highly tnllammable \f gaSi 
.able, naphtha, kerosene, or diesei 


(gj If a good bearing is not. to be imtncdbteiv placed 

back ii yervtce, v. mm be dipped m rus? preventive 


" ^.~"*»- ^^^ ^^ — i " — 

and . allowed to so.k unnl all dirt and grease have This rroubie m-v be host rccognf/ed br no i>V opera- 
loosened, This may require several hours, ii a \vire. cion of the betaHUg. . ' Upoti .removal - and after very 

mesh basket, similar ro chat shown 'in Figure 16- 7, is thorough cleaning, the bearmg vv.ill be noisy when 
ivadabte it should be used lor the soaking j^nod-.:. . rotated by hand (bearing* should never' be. spun by 

compressed air). Roughness may indicate spafimg 

Otherwise, a wire hook mav be fashioned to hold the 

.. .;>>:• 


dirt can cause- *w identical symptom, the prelim ma rv\ The trend in design \% to dim inure, as -nearly "as. pos- 

00 Orf/ >>> faftej* SlUrfll ^Wfete of din that enter / jrfLf§ 

thrbeiim-.^ in^vtounn r,*ppcti between ,t mite/ and the 

raff : - *^ ■>--* *~«w 

" iMsmt • - - .' .wr^-n -U, s NAVY 

Hrind Hue receive s as mime from its similarity to • 


An// h,l^ r i n „ 

Ballbearing Ratlar tearing 


.... or off sfiiarti This condition 
may be due poor condition of the shaft or the hous- 
ing shoulders Iris so.caccinics possible to detenmuc 
whether a bearing jfias failed due to muaiigntnene by 
observing the trace or path of the hails bo the races, If 
the path is not parallel co the : sides #f thfefc^ritog, it is 
probable that either the inner or m ttt race has been 
cocked. Figure 16- VI ■ illtmrates a spaced outer race 
caused by misalignment. The cmdiuon'M-ihis bear- 
ing indicates that h t VxS properly aligned originally 
and liter misaligned. When installing a bearing ? par- 
ticular care m'ust be taken to sor that ix is seated . 
squarely, and that neither the shaft uor housing is 

2 P^patr. Ball or toiler. '>bearmg5':ex.hib.iLdn:g spiii- 

s>2? ••• 

to determine the cause of the damage so that", similar 
damage to the replacement rearing may be verted. 

„ — 

' §§1 

' .' •- ^ 

This trouble b bat nxDgni'wJ by inspection of the 
rate*. "alter a thorough cleanup Figure ifrJ2 jJIus- 


(a) Improper installation or removal. Frictionless bear- 
ings are more difficult to remove than to install. Con- 
siderable care must be exercised to avoid damage to 
the bearing during removal. Figure 16-12A illus- 
trates damage caused by improper removal. This 
particular bearing was damaged by hammering 
against the outer race as shown in Figure 16-13. 

Similar damage can be caused by using a bearing 
puller or drift pipe on the outer race. Figure 16-14 

illustrates three ideal bearing removal methods. Note 
that in all cases, pressure is applied to the inner race. 

In removing a bearing with a press (see Figure 
16-14B), it must be made certain that the two flat 
bars make good contact with the inner bearing race. 
Where it is impossible to position the flat bars pro- 
perly, it may be necessary to employ a split ring 
similar to that shown in Figure 16-15. This same 
ring may be advantageous for removing the bearing 











rwa em socrj 

crs rtt/sr Be /*o**usrco 
'to nccr *>ul.l. c*C*f 

Digitized by 



Figur* 16-14. Corrmct mmthods of bmaring rmmoval. 



with a drift pipe. fSec Fivore l«~J4A,) M' 

recti? positioned on die mixer race. The pull must be V:\'.-' HSI I HPJM ' s 

tnadestrjighr and *p>»re, withm inspection ac fre- , «4g | a 

quenr lium Jls uv injure j^amfet cocking. In every ^ gu ^ - 0w e of wof<l,of - 

case, the •■shaft and tools must he thoroughly clean.. C^ftf/ jW pmwt'wv. Separator foiiwrc'is/freq'uenrly- 

*e occurs when the* tool 
the reUuvelv soft sepa- 

allcny* iss removal without . damage, to/the heat- to the -separator; Damage oti 

treated vh^t; a nd 'bearings. ' slips and bites inter ot bends the r 

<b* Vihnmm uMk form; h wptrativ*. Jf heavy raw Only the proper cooLs wmt 

shaft* supported by fncripnfess -bearings are allowed recnoval. See 

tosnmd qtauriw for 4, long rime, an J tf rh* equip. ^ f/ ^ . |J S8 

this time.. britici'irtB irt^v iir.L.if'. This is Hur m the ^ ^ r^jh xhe uuroduc uon of <^ 

this tio>c, brtucOi^ mav COT. Tim is due to "the * T ™ lx or the wnniucu on C 4 Struct ive sub-« action of the mlkis on. the races. Figure stances betwra b*li$ .or-mllm and the separator 
16- Hfl rf.u WS the severity of the bnneWto be Mad 'Mr*^ ua wedge to the^ror: 

v ? * p9rwv* ft i f *f T'b' 

and fitted- to the race 
cvtm thikrtools iitt hot 
re of t hi § bushing md the 

tng dust into the beuntyr- f« % 
it dun-a, jind mdt our the beeswax, Whe« . tools for 

• rerao 
m the axis of 

i **« v ui vu^u^ - bearing will be jfq 
with no apparent surface disintegration, . &$ many 

prevmm, Wear of be^ings; causing 
looseness vrabou* apparent surface disintegration is 
caused by the pr^ence of fine abrasive in the lubricant. 
Very fine abrasives, sibA as lapping compound, dust, 
etc, i» tfa*lahtkant mil cause a high rate of wear of 

4^* : ilv : -'^^: : .-.l<f;^l ..-^ -i?:- ^ tm.. >. . i i . , • _ _ _v 

1. W p M , The most fre^cne cause of *? ^U,or rolte wuhou, spalhng. The jfrhwo of 

acrac^cd race i cock in.; the bearing during Install ? u ) phWr X ° f " ^ hearing The 

rioo or removal. If the Lnng « forced o/or off the ~ "f^f ^ 

shaft while cocked, crack ing may occur. Rearing* ^ a ' F " cn ° «■ « 

-i , j i_ _ ! i " - .... p— »_. ? ft/fta/r Wnrn hpartrinfs must', foe rrl^jlWl rhmr 

should be in&ulJcd with «:are. See (a) Improper • ^ ^'f'"'; *«|» ^M.tocj«pia«^^;ttey ; 

2. Rt/Wr. Bearings with cracked fates must be diameter smaller than thai specified m the eng'itic 

it will route ac only one-half crankshaft speed. 

,< , v ^ /'. r "777 7: •' ' ' - 7; .7 1 

.... * ' 7 

mm m 

' > * ; $y#v? >*^iar ^.'^tf!' 

r - ■ : f * 

• ,T t / J 



ill i% 


$ '■■ ■ 

i*JwH£? -389s- 


• • • 

y -\ . v.^ 4 < 

* If. - - %TV £«0LC 

Got gle f '""' ' ' ^^ cmm 



' ' : - Ku t 


uncom mm** Salt water or add within the oil is very at vdrtdm mtiad speeds, torsional vibrations arc 

. the piay between 

^ \/ ; v surfaces of tfie leech in rnesti U \h uie^gujcd at the 

point of least pUy t Ir increases with wesr and can 

increase considerably wirhouc c*ayl^g damage. How- 

* v ever, oxcssi vs backlash can be very to the 

" r '" : gefes and car* cause gear failure U *J$o will change 

cattfshafr fuel pump, and vupercbarga t*mir*g, caus- 
ing the engine to operate inefficiently and hucortecdy . 
h h w»W /Jrvcr^ r<* te&Af* during 

Q$Mit$fynmrnt.. ' Faulty alignment between mesfe- ..Mr rc|*/ar pcrtctte msptcTion of tht par&Mti. The clear- 

ft 9W *17~$, pititd w 

to see chat auxiliary couplings &p aligned accurately fash measurement. If the readings 2 vc for excess of 
before bem^ bo! rt- d io^echtrr Gear a] rgptnenr par u- the speeiheu amount, the gear 

cularly important in reverse and reduction gear units. 
The pinions and gears must Une up perfectly or vibra- 
tion will be induced chat will cause gear failure. 

On . • 

gears roust be - replaced. 
Frequent "vospectiom's. for- scoriftg. together with an 
ade^u^cr supply of pure luhncai iog oi l and main ten- 
auce tit the proper clearances, will rend *o prevent this 
trouble. Excessive; backlash jn governor drives may 
often cause governor bunting, Wear cannot cake place 
without metallic, contact, which will cause ..*co ring 
of teeth. In the installation of gears, any misalign- 
ment will cause improper rootn contact, attd rcsul; in 
we*r. Fibre -'gears .iriore quick! v than raetai 

gears. Figure VI -1 shows a fibre gear that is almost 

■ V 



kept away from fibre material, if not/ the material result of some. metaJ obstfttcuon lodging between 

kept away from fibre material;, if not, the material result c 
will soften and fail. meshing v 

proper moth cootaci. as well as a scored sh at r somi i 

i to bushings. 1ft cmt cemm in- in 

? buying vvoire considerably, caus- ia, 

Jigamem ^ the that will h, 

rheidter gear bracktt and failure of the tmire difference 

studs ifc 

:ot ; si\«:hoda are used a ? repair bases aatf s*fyagt 


sages, jets and sprays, should be swabbed or blown out 
to insure free oil flow. Woodruff keys, dowel pins and 
other locking devices must be maintained at a tight 
fit, to prevent longitudinal gear movement. Every 
effort should be made to insure that all particles of 
broken gears are removed from the lubrication system, 
before new gears are installed. 

Special precautions should be taken that an engine is not 
barred over, while camshaft actuating gears are removed 
from the train. There is danger that the piston will 
strike any exhaust valves that may be open and ex- 
tending into the cylinder, if the engine is barred over. 
Under such circumstances, it should be made certain 
that any gears removed are replaced in the same posi- 
tion, with reference to timing. Special punch marks 
arc on teeth that should mate. If they are not, every 
effort should be made to install these marks to facili- 
tate the correct mating of the gears. 

The proper bearing, bushing and gear clearances 
must be strictly maintained. If bushing clearances ex- 
ceed the allowable value, the bushings must be re- 
newed. The allowable values for blacklash and bush- 
ing clearances can be obtained from the instruction 
manual for the particular engine involved. Sec Figure 
17-11 for an example from an engine instruction 
manual showing a gear train with allowable clearances. 

There is not much that can be done to repair a 
broken or chipped gear. In most cases, the gear has to 
be discarded and replaced with a new gear. Care should 
be exercised in determining whether a pitted gear 
should be replaced. Gears that are only slightly pitted 
should not be discarded. 


1 7C1 . Chains. Chains are not only used in several 
engines for camshaft and auxiliary drives but are also 
used in other engines to drive certain auxiliary rotating 
parts, such as supercharge valves, etc. In Figure 17-3, 
an example of a chain drive, it can be seen that gear 
drives are also used in conjunction with the chain, the 
water pump and overspeed governor being gear driven. 

The chains mesh with sprockets keyed to the shafts. 
One type of chain construction in use is shown in 
Figure 17-12. The two ends of the chain are joined by 
a connecting link secured by cotter pins. 

a. possible trouble: 
worn or broken chains 

The outstanding causes for the wearing or breaking 
of chains are: 

(a) Chain too tight. 

(b) Chain too loose. 

(c) Lack of lubrication. 

(d) Sheared cotter pins, 
(c) Misalignment. 

(a) Chain too tight. Excessive wear will be evidenced 
if the chain is under too much tension. The chain will 
become overloaded and subject to breakage. Excessive 
wear in fuel pump chain drives will become evident by 
retarded timing, which will cause a combustion knock 
and generally inefficient engine operation. The cor- 
rect tension in the chain should always be maintained. 
Reference should be made to the engine instruction 
manual for the proper procedure for obtaining correct 




BACKLASH .001 -.002 



NORMAL BACKLASH .002 - .003 



BACKLASH .003 -.004 

Digitized by 

Go gle 

Figure 17-11. Engine gear set. 


Go gle 

Digitized by VjUU^ 1C ^ 



Digitized by VjOUyiC ^ 




18A1. Introduction. The function of a drive clutch 
is to provide some means of disconnecting the engine 
from the propeller drive shaft on direct drive engines. 
In some direct drive engines, where the engine is direct- 
reversing, no clutch is employed. Clutches are of 
three types: friction, dog, and fluid. Clutches are ad- 
vantageous in that they increase the maneuverability 
of the engine, eliminate propeller drag on a dead en- 
gine, and lessen the load on the engine's starting system. 

18A2. Friction type clutches. Friction clutches 
are of two general styles, the disk style, and the band 
style. Troubles encountered with both styles are in 
general the same. 

a. possible trouble: 

Slippage is probably the greatest drawback to the 
friction clutch. This condition causes decreased effi- 
ciency, loss of power, and rapid wear of the clutch 
friction surfaces. Slippage is encountered mostly at 
higher engine speed when the engine is delivering the 
greatest torque. It is often hard for an inexperienced 
operator to recognize this trouble, but there are several 
items that should be noted that may give an indication 
of slippage. They are: 

(a) A gradual decrease over a period of time in the 
force necessary to engage or disengage the clutch. 

(b) Overheating of the clutch and clutch housing. 
Slippage results in energy being lost as heat. Some- 
times the overheating will cause a distinct odor. An 
alert watch should be maintained for this symptom. 

(c) A decrease in the speed of the ship for a given en- 
gine speed. This is difficult to recognize and usually is 
apparent only over a long period of time. It is gener- 
ally most noticeable when operating in a formation 
with other vessels. 

Digitized by »Ql£* 

(d) Noting and comparing the engine and propeller 
shaft speeds. Both the engine and propeller shaft 
speeds should be determined with a revolution counter 
and a stop watch. The shaft speed must be corrected 
for any speed change caused by reduction gears. 

1. Causes and prevention. Conditions contributing to 
clutch slippage are: 

(a) Wear. 

(b) Insufficient pressure. 

(c) Overload. 

(d) Oil and grease. 

(a) Wear. While clutch slippage greatly increases 
clutch wear, normal wear resulting from extended crt~ 
gaging and disengaging is often the cause. Clutch sur- 
faces consist of one or more steel surfaces upon which 
it is customary for the clutch facings to bear. Clutch 
facings are of several types which vary from soft 
metals, such as copper and brass, to molded and woven 
fibres, all of which must have a relatively high friction 
factor with steel. When the thickness of the facings 
decrease, it usually means that less pressure is brought 
to bear between the clutch surfaces. This tends to 
cause slippage. Another danger encountered with wear 
is that in the extreme case, the backing of the clutch 
facing contacts the finished steel surfaces. This causes 
scoring of these surfaces, which necessitates either 
refinishing or replacement of the damaged parts. 

(b) Insufficient pressure. Many clutch systems are 
provided with means for increasing the pressure be- 
tween the clutch surfaces. If such is the case, it is nec- 
essary to adjust the clutch from time to time in order 
to compensate for wear and to prevent slippage. 

Several clutch pressure systems are not adjustable, 
but are dependent upon the initial compression in the 
pressure springs, as in the twin disk units on Gray 
marine engines. With this system, it is important to 
check the springs whenever the clutch is disassembled. 




This should be done with a spring tester; however, if 
none is available, a check on the free lengths of the 
springs will give an indication of their condition. The 
instruction manual should be consulted for the proper 

(c) Overload. Overloading the engine is likely to 
increase the torque to a value where slippage will oc- 
cur. Whenever the engine is fully loaded it should be 
observed closely to determine if there is any slippage. 

(d) Oil and grease. Friction clutches are either of the 
wet or dry type, depending on whether or not they run 
submerged in oil and grease. It is important that the 
dry type clutch remains free of oil and grease, as a 
small amount of either is apt to cause slippage. Oil 
and grease usually reach the clutch surfaces because of 
the operator's carelessness. The clutch bearings should 
not be over-lubricated, as the excess lubricant will find 
its way to the clutch surfaces. When overhauling a dry 
type clutch, the parts must not be handled with greasy 
hands. All grease spots must be removed with a clean- 
ing solvent or carbon tetrachloride. 

2. Repair. When slippage is apparent, steps must be 
taken to eliminate it. Operation of a clutch with 
slippage soon wears out the clutch surfaces. The thick- 
ness of the clutch lining when slippage has occurred 
should always be checked. If the lining is excessively 
worn it must be replaced, for it is not sufficient merely 
to tighten the adjusting device if one is provided. 
When the lining becomes excessively worn, it will, in 
all probability, score the mating clutch parts, if not 

b. possible trouble: 


1. Causes and prevention. Clutch wear and slippage 
are much the same in that either can be the cause of the 
other. Excessive wear is caused by : 

(a) Engaging clutch at high speeds. 

(b) Rough surfaces. 

(c) Slippage. 

(a) Engaging clutch at high speeds. The engine must 
not be raced when engaging the clutch, either ahead 
or astern, as racing only adds to the wear and the load 
on the whole drive system. 

(b) Rough surfaces. Rough clutch surfaces will cause 
rapid wear of the clutch linings. Care must be taken 
not to damage the surfaces when overhauling the 
clutch. Any small nicks, etc., should be smoothed 
with a small stone. If the scoring is serious, it will be 
necessary to refinish the surface or to replace the parts. 

Digitize;: by (JO 'QIC 

(c) Slippage. See A. Possible trouble: Slippage , page 

2. Repair. When the clutch surfaces are worn, it is 
necessary to replace them. The cause of the wear 
should be determined and all necessary corrections 
made when replacing clutch parts. 

c. possible trouble: 


When a clutch fails to disengage, it is said to be 

1. Causes and prevention. A frozen clutch may be 
caused by: 

(a) Defective clutch mechanism. 

(b) Water. 

(a) Defective clutch mechanism. Whenever a clutch 
refuses to disengage, the clutch operating mechanism 
must be inspected. Where applicable, the following 
items must be checked: control rods, for obstructions 
or loose connections; excessive clearances in the 
mechanism; throwout bearings; pressure plate; pivots; 
and loose adjusting screws, etc. 

(b) Water. Moisture will cause molded type clutch 
linings to swell and to become soft. Many linings 
become sticky and tend to stick very firmly to the 
mating surfaces. The best way to prevent this trouble 
is, of course, to keep the clutch disk dry. Accidents do 
happen, however, and should a molded clutch lining 
ever become wet, it must be allowed to dry in the 
disengaged position. If allowed to dry in the engaged 
position, it will probably stick firmly to the mating 

2. Repair. An inspection should be made for defec- 
tive parts or improper adjustments when disassembling 
a frozen clutch. The clutch will have to be broken 
loose and thoroughly cleaned. If the clutch linings arc 
water soaked or worn, they must be replaced. 

d. possible trouble: 
chattering clutch 

Clutch chatter sometimes occurs when engaging the 
clutch. Serious clutch chatter may damage the reverse 
and reduction gears, and may cause the clutch linings 
to break loose, resulting in complete clutch failure. 

1. Cause and prevention. Clutch chatter results when 
dry type clutches become fouled with oil, grease, and 

To prevent clutch chatter, every precaution must be 
taken to keep oils, greases, and water from the clutch 
parts. When the operating mechanism is being lubri- 




■».-'•.'■ . ,-j • • 


- Causa and prwamon. The tufcukr type iiirshahv 

selves ->>- v irh- and -*r- ^reventc"! trem *hiHri> their the inner cohv. wifh the, result thai failure. is hketo 

. relative positions by the svochrofu^ers,. which are , , ' V'* 
otter, used to aid in .bringing the twhaks to equal. J ( ^^f* ^ 

T r i ; V ; '* ; f T chechuch, Most of chit tubular ait-iuifts have 

the .hitting lever sv.H allow relative monoo _, lC c..H,, a redc^ned . vpe. or ha- , lu-en modi- 

froio the : Corpora fimi dated tj'ulvl^41;< 
which can be obtained from the Bureau of Sh 
T<> remove th^ ^irshaft, a hole i 

— Mm I Mil in I iiiiiliirtimii^^ 







1. Causes and prevention. This trouble will occur as 
a result of: 

(a) Overfilling the gear case. 

(b) Foaming of oil. 

(a) Overfilling the gear case. Oil leakage is often 
attributed to overfilling the gear case. This causes the 
oil to flow out of the shaft bearings and onto the 
clutch drums. When filling the reduction gear case 
with oil, only enough oil should be added to bring it 
up to the full mark. Oil should not be measured or 
added while the gears are turning, for it is impossible 
to get an accurate oil reading when the unit is in 

(b) Foaming of oil. Foaming of the oil will result in 
oil leaking from the shaft bearings. Foaming may be 
caused by air leaks in the oil suction lines, or by over- 
filling of the oil pump. If foaming is apparent, all lube 
oil lines should be checked for air leaks, and to make 
sure that the level is not above the full mark on 
the gage. 

2. Repair. The clutch facings must be cleaned and 
all oil removed from the surfaces by means of a dry 
cloth. Kerosene, diesel fuel, or other solvents must 
not be used as a cleaning agent. 

d. possible trouble: 
pressure contact maker 

A pressurestatic contact maker is provided in the 
clutch air line to prevent operation of the clutches 
when the air pressure falls below the safe operating 
level. Considerable trouble has been experienced with 
ruptured bellows in the contact maker. The contact 
maker is connected electrically in the interlock of the 
control system. Thus, when the contact maker is not 
functioning, the electrical control system will not 
operate and manual operation must be employed. 

1. Cause and prevention. Rupture of the bellows is 
caused by vibration of the gears. The contact makers 
were originally mounted directly on the reduction 
gear case and therefore subject to all the vibration of 
the gears. To prevent the occurrence of this trouble, a 
new rubber mount has been developed that isolates 
the vibrations of the gears and prevents damage to the 
bellows. The newly developed rubber mountings are 
available for installation and should be installed on 
all units as soon as they can be procured. 

2. Repair. Ruptured bellows within the pressure 
contact maker require the replacement of the entire unit. 

Digitized by CjOi KjlC 

e. possible trouble: 
clogged air filter 

An air filter is provided in the inlet line to remove 
all water and other foreign matter from the air before 
it enters the clutch glands. The filter consists of a 
special stone made of aluminum oxide crystals bonded 
together by an acid resisting medium, forming a rela- 
tively high-strength porous material. The filter is 
built with a trap at the bottom to catch excess conden- 
sate. The trap is equipped with an opening at the 
bottom to facilitate drainage of the condensate. A 
clogged filter will cause air pressure to build up slowly 
in the clutches, resulting in slow operation when going 
from ahead to astern or vice versa. 

1. Cause and prevention. Failure to clean the filter 
will result in clogging. A clogged filter indicates that 
it has been performing its function, but that the opera- 
tor has been neglecting his. The filter case should be 
drained once each week, and the element removed and 
cleaned once each month. 

2. Repair. The air filter element should be removed 
from the case and cleaned in carbon tetrachloride or 
other approved solvent. The carbon tetrachloride is 
very efficient, but has a toxic effect on personnel. It 
should be used only where there is sufficient ventilation. 

Allowance lists call for a spare filter clement on 
board, hence it can be installed immediately after 
removal of the clogged filter element, thus shortening 
the time that the clutch system is inoperative. The 
clogged filter should be cleaned before it dries out and 
then stored until needed for replacement the following 


While the Airflex clutch can absorb slight mis- 
alignment between the engine and the reduction gears, 
excessive misalignment will cause the load to be con- 
centrated on the ends of teeth of the reduction gears, 
resulting in excessive pitting and eventual failure. 

1. Causes and prevention. Misalignment may be due 

(a) Change in engine foundation. 

(b) Loose hold-down bolts. 

(c) Permanent distortion of ship. 

(a) Change in engine foundation. The most frequent 
cause of misalignment is the settling of the engine on 
its foundation, or distortion of the foundation incident 
to beachings. To align the units properly requires 
extreme patience and care. The procedure outlined 

Original from 






VARIATION* 0.025" 



















Figure 18-3. Checking angular and parallel alignment of 
propeller shafts. 

under 2. Repair, below, should be followed for 
checking the alignment. 

(b) Loose hold-down bolts. All hold-down bolts 
should be checked periodically to insure that they are 
tight. Failure to do this may result in the unit shift- 
ing and becoming misaligned. 

(c) Permanent distortion of ship. Heavy seas or beach- 
ings may cause a permanent distortion in a ship which 
may in turn cause misalignment of the engine and 
clutch, or of the propeller shaft and gear shaft. It 
is impossible to prevent the occurrence of this, but 
the damage incident to the misalignment can be mini- 
mized by checking the alignment frequently. 

2. Repair. The following procedure should be em- 
ployed in checking reduction gear shaft alignment: 

Alignment of engine to gear. 

(a) The reduction gear must be placed in its nqrmal 

Digitized by 

Go gle 

running position by lining up the faces on the clutch 
gland flange with the reverse drum. This may be done 
by placing a straight edge across the full face of the 
gland flange, and checking the position of the clutch 
drum with respect to the straight edge. 

(b) A dial indicator is clamped to the clutch gland 
flange so that the parallel alignment may be checked 
on the outside of the reversing clutch drum (sec 
Figure 18-3A). 

(c) The reversing clutch drum is inflated with air 
at 50 to 100 pounds per square inch. 

(d) Starting with the indicator set at zero, the 
entire clutch assembly is rotated through 360 degrees, 
taking readings at quarter points (90° apart). The 
readings must be within 0.015 in. in 180° of clutch 
rotation for parallel alignment (indicator reading on 
outside of drum). 

(e) The dial indicator is next clamped to the gland 
flange so that the angular alignment may be checked 
on the after face of the drum. (See Figure 18-3A.) 

(f) Starting with the indicator set at zero, the 
entire clutch assembly is rotated through 360°, taking 
readings at quarter points (90° apart). The readings 
must be within 0.025 in. in 180° of clutch rotation for 
angular alignment (indicator reading on face of drum). 

(g) The shims must be adjusted to obtain indicator 
readings outlined in steps (d) and (f)- 

Alignment of gear shaft and propeller shaft: 

(h) With the coupling bolts removed, the angular 
alignment of the gear and propeller shafts must be 
checked b^ inserting a feeler gage between the flange 
faces at quarter points, that is, 90° apart. (See Figure 
18-3B.) The readings must be within 0.002 in. in 180° 
of shaft rotation for angular alignment. 

(i) The propeller shaft should be rotated 180° and 
the feeler gage measurements repeated at the quarter 
points. Again, the readings must be within 0.002 in. 
in 180° of shaft rotation. 

(j) With coupling bolts removed, a dial indicator 
is next clamped to the gear shaft to check the parallel 
alignment of the gear and propeller shafts. (See 
Figure 18-3C.) 

(k) Starting with the indicator set at zero, the gear 
shaft is rotated through 360°, taking readings at 
quarter points (90° apart). The readings must be 
within 0.004 in. in 180° of shaft rotation for parallel 
alignment. The gear shaft may be rotated by means 
of the engine jacking gear. 

(1) The propeller shaft is next rotated through 180° 
and step (k) is repeated. Again the readings must be 
within 0.004 in. in 180° of shaft rotation. 

(m) The shims are adjusted to obtain the alignment 





the, engine and •gfcar have ^ame fmnnbiJons, .die - nu *™?". , - : ^ :: < : ;/ ;\\ - ' ' / ' - — — _ 
l^ear duujjd first he attuned co r he propeller fcfuk," TmubJe ir^ Lfcn e'cpeneiit^d with bin-rung of the 

• ' .*.-. : ' • s - . • ' . : . v.- 

as tiscJ uu some LSM, PC, :md PCE vessels is similar tuUn £> lts lL P * 

ta.tfar:R>lk Airtlcx cimeh. Howwr, m the Fawiek . . 1. .CaSises atid prrrentfcjt. This tronhic 1a <..*used by 
clutch, the asbestos friction blocks arc riot molded to the friction blocks &t*%gibg on the drums when disen- 

Cl>) SwtltfH&df tk rMtr tin, Dragging may also be . chc clutch a c the same cimt. 

/caused hv the swduat> of the rubber tire due to its '< m '' T . .,. . , . T , i , » 

™„„ '.s.k ,„n> , .1 8 A6: Twin JiiJc ^iitck The rwm due dutch 

should be examined and repaired necessary; . W. . .. a. Kr 

drying is dsspectjed and invc^cfg^tiojrj reveals that _ _ wore 
the tire ;\h*x bled properly, the trouble is pmbablv \ " 1 i v ~> 


> - . " p r 


grease bp the dateh sorfaocs. Grease wiii caose dutch 
slippage, ot'erhearing, acid wew. In extreme cas^s, oil 

m m 

coo tntich grease whc» they do lubricate it. The ^ 
cess leaks cnit and finds its : way w the clutch surfaces, ' 
(b) Ltahtp of *H from rmr main 

*rtn^tthi> rLuC Aoul^ By 

and excessive 
cap muse be 

bcccgdo^. arertpJa ^ 

2. K^/f Whea excess grease is found on ebe clutch _ D . ; x , . . i . , . 

plates of the TwmDtecteeh, a, nccr^ry m .cm- . 2 " fft* ■ , 1q J* f 

plctelv drsasscmbie rhc dutch «tm and to rWo^hly jboa,d r / ^ " 

dWalJ *am with carton tetrachloride, .asolinc. or advent ut fi.qucnt-^^ K n, tf.erse 

18A7 JoeVflww, Joe's gears fw* Figure 18-6) 
employ i wo type* of dutches: a* disk type for - : — - 

• ■ . , - •••'('• ••< ' •-• r; Y ^ 'c - 1 ; - . 



Or ro allow fur 

(h) if th* shafts ate iWfcriy aliened fscc ft) 
above), the, Hue of A minus- 6 wli then id! the 

■ - i ■ i ■ i 


~ 00*5* CAMPiNG 




I j 



2. Kc^/r. Tn rid the nozzles of the foreign materials, 

it is necessary that Asv he ,.t^\^"gihd bl^wa out, A 
DRIVING m&W- ~™ -i^.^i 

* ' > "'" * co '-^ r r,he obstruction, U vviii Be necessary io secure 

W thc engine arid remove a'ru! clean rhi -nobles. 


I i 


Fi^W J 8-70. fttfirmUc co..*(V»«. 9 «d 4um» ^*^*3HBBI 



necessary ro maintain '■.the . oil syirem free frocu aft dirr , » '- '-^^ 

and scale. In some Cases, the foreign materia} has been jJK£'*'W8$- •• •"' : ' •■' 

gasket compound and in other cases, shredded copper •- *4 . • , , 

from mi tube packings. Wb a rcver the foreign partides • ■ 

W;-' M •:• • • • bst'M 

» » - •. • • . -1 f. • .!.» -. \ - .1 •. • 


jo of shw trouble can be accompfisilfid W not ^ »P .**' * totAi '<*?• Man >* W of this 

ch-4B«ifl^ of the tube oii If ao arid coadirioa W spitting have. de.*red up foitawmg further >eai 
;ted, ^ .' sample of . the lubricant *oliid be afihtgesr, 

Prevent ion 

periodic changing of the tub- 
is suspected, 'i» sample of rhc lubricant sho 
•analyzed if itn syvitLWe i.ilxrtatory,.. 

.J 1*., • ....................... . ■., •> 


across the full width of the gears. (See Figure 18-16.) 

Many cases of gear misalignment and subsequent 
pitting are directly attributable to improper position- 
ing and alignment. Whenever this type of pitting is 
apparent, the alignment of the shafts must be checked 
and corrected. 

This type of pitting may indicate that the internal 
gear alignment of the shaft within the gear case is at 
fault. Since provision is not made in some of the 
smaller gear cases for aligning the gears, the only pro- 
cedure possible is to replace the gear case. Where 
realignment of the shafts and gears is possible, it 
must be done in accordance with the instructions set 
forth in the instruction manual. 

(e) Foreign particles. Particles in the lube oil will 
cause excessive gear wear, and will cause pitting of 
the gear teeth. When pitting is due to foreign particles, 
it will not appear evenly on all teeth, nor will it be 
evenly distributed on any one tooth. This trouble 
usually does not necessitate any repair of the gears, 
but it always requires that the lube system be cleaned 

Particles usually enter the system through inspec- 
tion plates and other openings. Care must be taken to 
prevent dirt, etc., from entering. The inspection plate 
must never be left off longer than is necessary to make 
the required inspections. 

2. Repair. There is really no repair method for 
pitting. The required action is, of course, dependent 
upon the cause of the pitting. If the pitting has been 
caused by corrosion or abrasives, the lube oil will 
require replacement, and the gear case, piping, and the 
entire lube oil system will require flushing to clean 
them thoroughly. The gear teeth must not be stoned 
or filed to remove pits, as this will make the condition 
even worse. 

A very satisfactory method of checking gear condi- 
tions is that of giving the gear teeth a thin plating of 
copper. This can be accomplished by cleaning the 
gear teeth thoroughly with a dry cloth, and then giv- 
ing it a wash with a solution of copper sulphate. 
(Q1SO4 can be obtained from sick-bay.) The copper 
sulphate solution should be applied with a soft rag. 
It is not necessary to treat all of the gear this way. It 
is usually sufficient to plate just a few teeth at 90° 
intervals around the gear. After the plating has been 
completed, the gears should again be put into service, 
and inspected after 6 to 8 hours of operation! Upon 

inspection, a clear imprint of the area of contact can 
be seen. The polished area, indicating contact, should 
run the full length of the gear teeth. If the alignment 
is incorrect, the polishing will be localized at one end 
of the tooth or the other, and indicates that realign- 
ment is necessary. 

b. possible trouble: 


Trouble has been experienced with gear oil foaming 
and running out past the shaft seals, causing consider- 
able damage. Oil leakages make for an untidy ship 
and present a fire hazard. On several machinery instal- 
lations, friction clutches are adjacent to, or integral 
with, the reduction gear. In such cases, gear and lube 
oil leaking from the reduction gear case and shafts 
will cause clutch slippage and deterioration. 

1. Causes and prevention. Oil foaming can be caused 

(a) Overfilling. 

(b) Air leaks. 

(c) Improper oils. 

(a) Overfilling. The chief cause of foaming is that 
the gear cases are overfilled. In an attempt to lubri- 
cate properly, operating personnel often add too much 
oil to the system. The oil level should be checked 
after filling to be sure it is correct, and not overfilled. 
The oil should never be checked or added while the 
gears are in motion. 

(b) Air leaks. Air leaks in the suction oil lines arc 
also responsible for oil foaming. Whenever foaming is 
apparent, the lines must be checked, and all loose 
connections tightened. 

(c) Improper oil. In rare cases, foaming has been 
caused by the use of improper lube oil. Some oils have 
a greater tendency to foam than others. Oils may have 
chemicals added to them which tend to prevent foam- 
ing. Rarely is foaming caused directly by the oil. The 
oil level and the suction oil lines should always be 
checked before considering the oil itself. 

2. Repair. To eliminate foaming, eliminate the 
cause of foaming. 

c. possible trouble: 


A complete discussion of gear failure is given in 
A, Possible trouble: Gear failure, pages 309 to 312. 

Digitized by tjOOQlC 





19A1. Ste^n gage. The BAurJoct type . fwsstife _ i* bqvroon. Ttmu . element 

<r^irc k the iiiosc common instrameftt for me^^urine 


B. possible trouble: 


This casualty is mentioned in order to stress the 
importance of giving immediate attention to the re- 
placement of a broken glass. If the gage is allowed to 
remain open to the atmosphere for any length of time, 
serious damage may result. Foreign material, such as 
dirt or metal particles, may easily enter into the case 
and hamper the free movement of the linkage, sector, 
and pinion. Any particle of dirt on the linkage will 
increase the friction of the moving parts and thereby 
decrease the accuracy of the gage. 

1. Causes and prevention. 

(a) Unnecessarily rough handling. 

(b) Severe shock or explosion. 

(c) Vibration. 

(a) Unnecessarily rough handling. This is the fault of 
the operating personnel entirely and can be eliminated 
by careful handling. // is to be remembered that these 
are precision instruments and should be treated as such. 

(b) Severe shock or explosion. Any nearby explosion, 
such as gunfire, will cause shattering of the glass. 
Scotch, or cellulose, tape placed over the surface of the 
glass is an effective method of preventing glass par- 
ticles from flying about the engine room. 

(c) Vibration. Vibration is discussed in another sec- 
tion, but too much cannot be said concerning the 
correct place and position for gage installation. It 
should be placed in a location free from all vibration. 

2. Repair. A broken glass should be replaced imme- 
diately. Spare glasses should be kept on hand for such 
an emergency. If the case is the new style phenolic 
type, no gasket is needed, but in the old type case of 
cast iron or brass, a felt gasket must be installed. 

c. possible trouble: 


This trouble is apparent if the gage reads zero when 
connected to a line known to be under pressure. 

1. Causes and prevention. Following are the possible 

(a) Gage line plugged. 

(b) Pointer loose on the spindle. 

(c) Bourdon tube element broken. 

(a) Gage line plugged. The line should always be 
checked as foreign material may completely stop the 
flow of fluid to the gage. The gage may be in perfect 
condition, with no repairs necessary. 

(b) Pointer loose on the spindle. The pointer may have 
been improperly installed, and is not secured to the 

Digitized by GOuQIC 

spindle. A pointer puller is supplied with the gage, or 
with any gage testing apparatus, and should be used 
whenever the pointer is to be removed. Care should 
be used in resetting the pointer so that it will not slip 
freely on the spindle. 

(c) Bourdon tube element broken. See A. Possible trouble: 
Hole in Bourdon tube element, page 329. 

2. Repair. To repair a gage having its pointer loose 
on the spindle, the following procedure should be 
used: The gage is placed under some pressure, say one- 
half of the maximum scale reading, and the pointer is 
removed by using the pointer puller. The pointer is 
next placed in its proper position on the spindle and 
fastened by a light tap. It cannot be twisted into posi- 
tion because the pressure and torsion exerted in placing 
it on the spindle will result in permanent injury to 
the mechanism. 

Figuro 19-2. Adjustment of Bourdon mechanism. 

D. possible trouble: 


The Bourdon tube is connected to the pointer by a 
linkage containing a sector gear that engages a pinion 
on the pointer spindle. For every movement of the 
tube, there is a corresponding movement of the pointer. 
The amount the pointer moves is dependent upon the 
ratio of movement between the two, as determined by 
the adjustable linkage mechanism (see Figure 19-2). 
If the linkage is not set in the correct position, an 
error of variable magnitude will be introduced. This 
error can be detected when the gage is calibrated. The 






talibratm of a gage is the compartscm of the gag« : wicb ewe** theseemrand the pivot point roust be length- 

a known correct, gage or gage tester,, i&d the recording ened to reduce poinjer traysl- 0) If %hc fainter does 

of the-' Wbtiaq between the two readings when both not travel far enough for a known pressure increase, 

are subjected to same pressures. The device used is a this linkage rnus* be shortened to increase the pointer 

deadweight tester (see Figure 19- -3). The tester: con:- travel. See Figure 19 -1 for these Mjustmentr 

sists of i hvdnuiic extern, one s«de of which ^ con- ; — ~- - - — - — - - . 

knowri cojrrect pressure. The pressure is increased -in ■ _ i Q^sfc uNtCAOhs *vn GbAti& ^ 

2 Rfj»ir, in repairing the cotnnioo type gage, my When the vibration is severe, a feible collection 

screw the right dimension riuy be used, but for the should be installed between" the gage and Jjh& If the 

nusre esgtusrve gages, a micxoaitfusttn^ ^crew is ascd. pressure fluctuate* violemlv, a pupation dampe^ef 

Adjusuftettts are mo in numbed, defending upon should he 

f'-csr upstream, 

>ue sate . 


2. Repair. Inaccurate gages that are in need of new 
parts should be sent to a repair ship. 

f. possible trouble: 
pointer does not read zero for 
atmospheric pressure 

This indicates an error of constant magnitude. The 
gage will probably be off approximately the same 
amount over the entire scale range. 

1. Causes and prevention. Such error may be due to: 

(a) Pointer loose on the spindle. 

(b) Permanent strain of the tube. 

(a) Pointer loose on the spindle. See (b) Pointer loose 
on the spindle, page 330. If the pointer is displaced, 
it should be set properly. 

(b) Permanent strain of tube. There is nothing that 
can be done to repair a tube that has been subjected to 
a stress greater than its elastic limit. The gage reading 
will naturally be off if the tube has been permanently 

2. Repair. Most gages have a pin placed at the zero 
mark of the scale. The pointer rests upon this pin at 
zero pressure. Some gages have this pin advanced a 
slight amount from the zero mark in order to have the 
pointer resting against the pin under a slight pressure. 
This is to prevent vibration when the gage is not in 
use. There is also a disadvantage to this pin. If the 
pin were not there (advanced from the zero mark), it 
would be easy to tell, merely by a glance, if the gage 
were out of order. The position of the pin should be 
checked, for it may have a lot to do with whether or 
not the gage reads zero for atmospheric pressure. To 
check the gage, the pin should be removed. For 
replacement of the pointer, see 2. Repair, page 330. 



t t 





Figure 19-4. U-tube manometer, open fype. 

Digitized by 

19A2. Manometers. The Bourdon gage can be 
used with reasonable accuracy for measuring lubri- 
cating oil pressures, circulating water pressures, fuel 
oil pressures, and starting air pressures. It may some- 
times be used to measure scavenging air pressures. For 
the measurement of the back pressure within the ex- 
haust manifold, another instrument is often used be- 
cause of the small pressure differential encountered. 
This instrument is the manometer. It is also used in 
connection with the pneumercator, an instrument to 
measure fluid height in the ship's tanks. Sometimes 
the manometer is also used for measuring scavenging 
air pressures and crankcase vacuum. 

In the manometer, a fluid column is used to measure 
pressure or vacuum, the height of fluid being known as 
feet or inches head of fluid. If a vacuum is being 
measured, the result is usually expressed as inches of 
water ("H 2 0) or inches of mercury ("Hg) vacuum. 
The simplest and most common type is the U-tube 
manometer, open type, shown in Figure 19-4. The 
bend is filled with a liquid, usually water aboard ship. 
Other fluids in use are mercury and oil. 

In Figure 19-4, if both legs are connected to the 
same pressure, the level will stand at an even height. 
However, if one pressure is greater than the other, the 
column of liquid will move until both pressures bal- 
ance each other. The difference in liquid level will be 
proportional to the difference in pressure existing 
between the two pipes. In the open type, one leg is 
open to the atmosphere and the other leg connected to 
the line being measured. A gage pressure is obtained. 
In the illustration, the left leg (atmospheric pressure) 
is subjected to the smaller pressure; that is, its level is 
higher. The value of H will be the value of the pres- 
sure within the line. 

If the manometer in the illustration were attached 
to a line in which a partial vacuum exists, the left leg 
of the manometer (atmospheric pressure) would then 
be subjected to the greater pressure; that is, its level 
would be lower. 

There are many other types of manometer in use, 
such as the inverted U-tube, closed type differential 
pressure, inclined, and cistern type, but these are not 
usually found aboard ship. It must be remembered 
that the liquid level of all manometers is subject to the 
roll of the ship. Only the open type manometer is 
considered in this discussion. 

Because of their simplicity, not many troubles are 
encountered with manometers. The operation of the 
manometer is dependent only on a column of fluid, and 
not upon a system of gears and linkages such as those 
used in the Bourdon gage. 

> Qrigiral from 



A. possible trouble: 


This trouble becomes apparent when the manometer 
gives a low reading when connected to a line of known 

1. Causes and prevention. Loss of pressure may be 
due to: 

(a) Hole in flexible connection. 

(b) Flexible connection not tight. 

(c) Clogged line. 

(a) Hole in flexible connection. The manometer is 
connected to the line in which the pressure is being 
measured, by a flexible rubber hose or other type of 
tubing. Loss of pressure will occur if there is a hole in 
this tubing, with consequent low pressure reading. 

(b) Flexible connection not tight. The hose or tubing 
should be tight over each leg or leakage will occur. 

(c) Clogged line. Occasionally the connecting line 
between the gage and the line of which the pressure is 
being measured, becomes clogged with foreign de- 
posits. This will give a low pressure reading. All 
connecting lines should be blown out if there is any 
indication that the line may be clogged. 

2. Repair. The flexible connection should be kept 
in good condition; kinks or sharp angles should be 
avoided when installing it. 

b. possible trouble: 
loss of liquid 

Water is probably the most common liquid used 
aboard ships in manometers. Sometimes it is colored 
to aid in the determination of its level. If oil is used, 
its specific gravity must be taken into account. Specific 
gravity is the ratio of the weight of a substance com- 
pared with the weight of an equal volume of water. 

1. Causes and prevention. Loss of liquid may be a 
result of the following: 

(a) Too great pressure. 

(b) Use of incorrect fluid. 

(a) Too great pressure. It is obvious that if a manometer 
is connected to a line under greater pressure than the 
range of the manometer, the liquid is liable to be 
blown out of the tube. The correct manometer must 
be connected to each line. 

(b) Use of incorrect fluid. Because of the difference in 
specific gravities, the different fluids in use will not 
move the same height under the application of the 
same pressure. It is evident that if the incorrect liquid 
is used, there is a possibility of the liquid rising com- 
pletely out of the tube. 

Digitizes by GO «QlC 

2. Repair. Before replacm^ 
need cleaning. A dirty tube will nil... ^ tU ^e may 
tion of the correct liquid level. Dirt, rusi,^flnfla- 
collect on top of the liquid and change the reaQvAk 
After the liquid has been removed, a solution of nitric 
and hydrochloric acid can be used to clean dirty tubes. 
Only clean liquid should be used when replacing. 
When replacing mercury, a medicine dropper can be 
used with a thin wire to guide the mercury into the 
bottom of the tube. Each drop placed on the wire will 
drop directly to the bottom and on top of the preceding 
drop, thus preventing air bubbles from entering the 

19 A3. Engine indicators. Engine indicators are 
used to measure cylinder pressures, both firing and 
compression. They can be used in conjunction with 
exhaust temperature readings to help diagnose opera- 
tional troubles. Most indicators generally used with 
diesels are either of the spring balance type or the 
trapped pressure type. 

The Premax indicator, model YBC, is of the spring 
balance type and employs: 1) a spring to balance the 

Figure 19-5. Premax indicator, model YBC 

Origiral frcrn 


£)/£^ _ - circuit to indi- 

c ylindc r D oafanced. 

Caf e when t ., SS1 ^' aiscusslon on tnc principle of oper- 
In^rjkcquent reference should be made to Figure 
19-5. The indicator is connected directly to the engine 
cylinder with the indicator piston (6) being exposed 
to the cylinder pressure. A helical spring (3) acts 
against the piston and the cylinder pressure. There is 
an index sleeve (2) that is used to adjust the spring 
compression to balance the cylinder pressure. When- 
ever the engine cylinder pressure is greater than the 
tension of the spring, the piston will be forced from its 
seat, closing the contact switch (5) of the neon light 
circuit. A visual flash will appear at the neon light 
flasher. The gas pressure will drop as a result of ex- 
pansion and the piston will scat, opening the contact 
switch. This cycle will be repeated every time the 
cylinder fires, giving a flashing light. 

To obtain a reading, the spring tension must be 
increased until the flashes just disappear, indicating 
that the spring tension is sufficient to balance and stop 
the movement of the piston. When this exact balance 
between the two opposing forces is reached, the switch 
will remain open and the pressure within the cylinder 
can be read from the scale. 

To obtain compression pressures, the fuel pump is 
cut out to the particular cylinder and the same proce- 
dure is used. 

The usual manner of obtaining readings is to take 
two readings for each pressure and compute an average 
value. These two readings may be taken by first turn- 
ing the index sleeve until the flashes begin to appear. 
The reading at this point will be No. 1. The index 
sleeve is rotated opposite to the previous direction 
until the flashes just disappear. This will be reading 
No. 2. An average of these two values will be the 
maximum cylinder pressure. This method of obtaining 
readings is also helpful in detecting whether or not the 
instrument needs cleaning (described later in this sec- 
tion). This indicator is a precision instrument. Proper 
handling, installing, and operating will reduce the 
troubles encountered. 

It is essential that the indicator be kept clean and 
free from all dirt, because of the lightweight parts and 
delicate design involved. Dirt in the bearings of the 
moving parts will affect the balance of the instru- 
ment. The indicator valve must not be left open longer than 
necessary. The high temperatures will not only de- 
crease the indicator's life, but will also make it diffi- 
cult for the operating personnel to handle. The wear- 
ing of gloves is a great advantage when pressures are 
taken. If they are not worn, there is danger of being 

Digitized by 

burned and also the extreme danger of dropping the 

The index sleeve should always be rotated to corre- 
spond to a zero pressure reading on the scale before the 
indicator is secured and stowed for future use. This 
relieves the instrument of all spring tension. 

a. possible trouble: 


Gumming of the piston is evidenced by a large travel 
of the index sleeve, at or near the balance point, with- 
out any flashing of the neon light. Both the piston 
and cylinder may be coated with a varnishlike deposit. 
If this deposit is allowed to accumulate, low erratic 
readings will be obtained. Gumming of the indicator 
piston will also be evident in a growing spread between 
reading No. 1 and reading No. 2, mentioned previously. 

1. Causes and prevention. Gumming of the piston 
may be caused by: 

(a) Failure to blow the connection out. 

(b) Poor conditions of engine operation. 

(c) Improperly lubricated piston. 

(a) Failure to blow the connection out. Before attaching 
the indicator, the connection should be opened to 
allow the exhaust gases to expel all carbon, oil, soot, 
and dirt that may have collected. If not, this material 
will collect and lead to a gummed indicator piston. 

(b) Poor conditions of engine operation. Incomplete 
combustion and excessive cylinder temperatures caused 
by the condition of the engine will aid in gum forma- 
tion. They make it difficult to keep the indicator in 
good working condition. 

(c) Improperly lubricated piston. The piston must work 
freely; a gummed piston cannot. The indicator manu- 
facturer recommends that in taking readings, a dry 
piston be maintained, as oil will tend to form deposits 
which cause sluggish action of the instrument. This 
necessitates wiping the piston and cylinder free of oil 
before the indicator is attached to the engine. How- 
ever, the piston must be lubricated after it is cleaned 
preparatory to being stowed for future use. This will 
tend to prevent rusting. Only a thin film of lubricant 
should be placed on the piston. 

2. Repair. While it is still hot, the indicator piston 
should be cleaned with a cleaning fluid supplied by the 
manufacturer. If none is available, acetone may be 
used successfully as it is effective in removing gummy 
carbon deposits. Compression pressure tests form less 
deposits in the indicator than firing pressure tests, due 
to the lower temperatures encountered. The type of 
lubricant and the parts to be lubricated before the 



Go gle 

Digitized by VjUU^ 1C ^ 


in irculliog. it should bephccd as. near Ac cylinder 
as possible and in a position that can be cosily read- 
Tb^ndtcaor^hown jn Figure 19-7 is cqnyctiienr to 

- ! uvk ; 


driest! pressure chamber. The chamber contains a check Ia Thejd«e«in£licatprs /rientioned, readings are taken 

l rest henrc rn«rrrsa >-rrr>r<! 

ouMMt.0 cmxK V,u.vr 

. — — : — ^ — 

Any um0g or gumming will cause leakage with 
resultimc mark, readings. This Jca kageom be sasiiy 
detected by flacfu^tions of the gcige hand ar low engine 
speeds mi a rapid decrease 1 'in pressure t£adm»:wh>n 


Repair, Leaks can be located wnh ixcmimg of 
i Aee^'teiar iof the io^rrumeht If the lekkis not 

at thej*>mt> the . indicator should be teitoatod frofti the 
cock and oil Applied ro detect JcAaep Mw fbc check 

, cloth. N^mnprmfifh^sthe u^do^ wtvr. Ml lapped h Causts and fnvwtion. The' ravsr g!a*w 

^cy *«* proper srow^c. 
(a} Cattle^ haHdlmgn Thtvmottmcrs should be 
handled carefully as they are cosily brakes 

mAtrml placed behind the cube. The temperature can . 
he read Jroip cbft scjlr drrcctl y. This thermometer raay 
appear uv several different; for 
tteiar roorcd , Sir *tg t, or an, 

■jskaKiM co^ra oi^ss enclose^ in she dement which- ii inserted directly iota 

. .Tb-i$.f*«!/<v,4eot.'bnt kis ine«cim«d here because me^ut? Mm^t Ts^ht f^id^^rtbe Naw"' 


(a) fmd type, A 

2. ftfju* There is no acttfa) repair tfeat cfn bc;.madc 
to this type other than tfce 'repairs to t he Sonrdon gAgt. . . ■jfE^ 


1. Cause and prevention. This trouble is caused by 
reversed connections. The iron wire of the thermo- 
couple should be connected by its extension lead to the 
positive terminal of the selector switch, and the con- 
stantan wire of the thermocouple should be connected 
by its extension lead to the negative terminal of the 
switch. If these connections are reversed, the pyrom- 
eter will read backwards for the particular cylinder. 
The two extension leads are usually of the same metal 
as their thermocouples. The iron wire should have an 
iron wire extension, and the constantan wire should 
have a constantan wire extension so that the cold junc- 
tion will be located at the pyrometer. 

2. Repair. The connections for the faulty cylinder 
must be reversed. The iron wire can be identified by a 
magnet if there is any doubt as to which is the positive 
wire. The constantan is the negative wire and is 
nonmagnetic. In several installations, the iron wire is 
identified by a black braid covering while the constan- 
tan wire has a white braid covering. 

d. possible trouble: 
pyrometer reads backwards for every cylinder 

This can be evidenced by the pointer dropping below 
zero when the switch is rotated to each cylinder. 

1. Cause and prevention. This trouble is caused by 
reversed connections; that is, the extension wires from 
the selector switch to the pyrometer have not been 
correctly connected. 

2. Repair. The connections to the pyrometer should 
be reversed at the selector switch. 

c. possible trouble: 


This can be evidenced by comparing the zero or 
open circuit reading of the pyrometer with the actual 
room temperature. The trouble is apparent if a serious 
difference between the two readings is obtained. 

1. Cause and prevention. This trouble is caused by 
incorrect adjustment. The cold junction is at room 
temperature. There is an automatic cold junction 
compensator that sets the zero (or open circuit) posi- 
tion of the pointer to coincide with actual room tem- 
perature. If this does not bring the pointer to room 
temperature, the pointer must be moved manually. 

The zero adjusting screw marked on the face of the 
instrument has been the cause of maladjustments in 
many instances. Some operators misinterpret the 
words "zero adjusting screw" and adjust the pointer 
to zero on the dial instead of to room temperature. 

Digitizes by GOuQle 

Make sure that the dial pointer is adjusted to room tempera- 
ture when the dial is in the zero position. 

2. Repair. To move the pointer, most pyrometers 
have a zero adjusting screw situated on the face. The 
screw can be turned with a screwdriver. 

d. possible trouble: 
incorrect temperature readings 

This can be evidenced by discrepancies when the 
readings are compared with those given by other tem- 
perature measuring devices known to be correct. It 
can also be evidenced if the pyrometer fails to operate, 
or when the pyrometer reads zero for any one cylinder 
when all the other cylinder readings are satisfactory. 
The extent of the trouble can be localized as to one 
cylinder unit, or to a trouble common to the entire 

1 . Causes and prevention. Following are the causes of 
this trouble: 

(a) Damaged millivoltmeter. 

(b) Loose wiring connections. 

(c) Dirty contacts. 

(d) Dirty thermocouples. 

(e) Grounded wiring. 

(f) Broken wiring. 

(a) Damaged millivoltmeter. The millivoltmeter is 
the instrument used to measure the voltage produced. 
The coil within the instrument can become easily dam- 
aged by rough or inexperienced handling. Its sensitive 
balance is easily destroyed, rendering it inaccurate. 
An open circuit can exist within the indicator which 
will give a zero reading. An open circuit can be deter- 
mined by a method mentioned under 2. Repair, page 

(b) Loose wiring connections. This is evidenced by 
pointer fluctuation. It can occur either within the 
thermocouple itself or external to it. The constantan 
wire and iron wire are welded together to form the 
hot junction within the thermocouple. This weld 
may easily break or burn loose, destroying the junc- 
tion. Within the thermocouple, the pyrometer wire 
terminal may have worked loose. (See Figure 19-16.) 
This could also occur at the selector switch terminals 
and indicator terminals. 

(c) Dirty contacts. The selector switch contacts may 
become coated with a thick layer of dirt, grease, etc. 
This will lead to inaccurate readings with the possi- 
bility of a zero reading. The contacts must be kept 

(d) Dirty thermocouples. After being exposed to ex- 
haust gases, thermocouple stems become coated with 



°F. This . ; 

shore circuiritag "of the dtrt:ftic;il wino? wJJ -prevent 
the operation" of the pyrometer , because of the minute 
voltage generated by a thermocouple m? u An average 
value for the Voltage prdfuted is , Jesrf riida otic- 
twentieth of a yak. « . .. * 

(Q Br&km wtrwg> kny broken wire will caasc the 

instrument to fail to read 

The selector switch contacts should be cleaned and 

before a reading can be taken 
po.ntcr will then swing frtelv 

This must be removed cimut Witi Occur 

circuumg or .^iuji<jitig of. the wiring, syston. ' if it 
become worn or burned through, shorting oat of the 

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l!§8l . V; '"■ ■ '■" •' " : : " ; ■ ■ : , ........ 

termini of cheebmoocaapie. The positive wiwinds • . , ' ■ - ■ * * 

must aisc- be in COOMCt With ihe positive prod, if a 'Snap switch (or controlling *Wom*w. -fUfercnt* J 

ti be no reading, H. 'Resistance .bulb 

.■._...)„ _ r..ii Hi. Resistance bulb 


({•>} iViiifiam contact. 'The "prods must he ia foil „, jx,,,^,,:, -it- -»,, 

• • trm mi^t iv . tk, th& : t'h?Ymiic.iiii rtlkr ' art f f • ' 

Hemp pack mo 
H3, Resistance bwib - Washer - f tat 



I is from an cxceroai source. A check engine ^iJaciom, nhe^horaerer is drive* 
q see if there is a dosed drtuu from right angle drive adapters and flexible cm, 


should be made c<» see if there is .a closed artuu from right angle drive adapters and flexible connections, 
the supply m the bulb and to the indicating instrument. The drive cable must be ins railed With rhe smoother 

(b) Qp«H cmuit en dxmcal i- n 
natural! y gi'v-c a -zero? reading 

fcy.prokm W ; The bulb is connected ro the i ndi- Hut 
cator by means dm ex region Cuhle; Any ^- 

cable will the indicator to Uii to reaa. r t ; ; 

be iDve^fT 

2. K#*fr. Ti^ saw precaution* that apply i:0 the re- e 

2, Rr£**r The cable must be. mstaHed properly. Ic 

, deter- serious .damage to the instrument . 

3 c*J tachometer The electrical . 
19-21) depend- foi its indication 
current generated hv a sm;iji direct 

the en^ne lubrt^uog oil system. ^ F a 

watch and 'tl*** 

• i 


fairly high voltage. The voltage is transmitted to the 
recording instrument, usually a voltmeter, calibrated 
to indicate speed directly in units of revolutions per 
minute (rpm). This instrument functions with the 
engine running in either the ahead or the astern direc- 
tion. The brushes are of a self-lubricating material 
and are carried in a self-aligning holder that equalizes 
the pressure on both brushes. 

a. possible trouble: 

pointer not at zero when engine is secured 

This is observed when the pointer does not read zero 
with the engine not running. 

1. Cause and prevention. This trouble is caused by 
improper adjustment. There is a zero adjusting screw 
on the instrument case in some of the installations. 
A slight turn of this screw will bring the pointer into 
its correct zero position. If the correction of zero 
reading is greater than can be accomplished with the 
screw, the instrument needs repair. 

2. Repair. A screwdriver is used to turn the adjust- 
ing screw. The manufacturer's suggestions should be 
followed as to whether the generator should or should 
not be dismantled in any attempt to service the inter- 
nal parts, other than to clean the commutator and 
brushes, as incorrect speed indications may result. 

b. possible trouble: 

pointer reads astern with engine going ahead 

The dial is calibrated to read in both the astern or 
the ahead direction. 

1. Cause and prevention. Improper terminal connec- 
tions are the cause of this trouble. The plus terminal 
of the generator is indicated by its relation to the 
crankshaft rotation. The correct rotating direction of 
the generator must be determined for the ahead direc- 
tion of engine rotation. The plus terminal of the ta- 
chometer indicator and the plus terminal of the gener- 
ator must be connected together. 

2. Repair. The connections are marked. The leads 
are merely changed to the correct terminals. 

c. POSSIBLE trouble: 

This can be detected by erratic operation of the 
pointer leading to inaccurate speed indications. A 
mechanical device known as a revolution counter can be 
used to determine any inaccuracy in the tachometer 
reading; that is, if the tachometer does not include a 
built-in counter to record revolutions. When a hand 
counter is used, it must be held horizontally and placed 

Digitized:, GOuQle 

directly against and into the indentation in the rotating 
shaft. The operator must not lean on the counter. This pre- 
caution is taken not only to prevent damage to the 
counter and possible inaccurate indications, but also 
to prevent personal injury. 

1. Causes and prevention. This trouble results from: 

(a) Improper grounds. 

(b) Improper electrical contacts. 

(a) Improper grounds. The case must be grounded to 
avoid static charges. In addition, if the wires run in a 
metal conduit, the conduit should also be grounded. 
The wires, however, must be kept free from all elec- 
trical grounds. 

(b) Improper electrical contacts. The generator, similar 
to all generators, requires periodic cleaning. The elec- 
trical contacts should be examined quarterly, or oftener 
if necessary, for pitting, oxidation, fusion, and wear. 
Anything that will change the contact resistance will 
change the voltage generated and thereby change the 
speed indication. Dirty brushes and commutator lead 
to high contact resistance. The electrical contacts at 
the terminals should also be inspected and cleaned. 

2. Repair. Extreme care must be used in cleaning 
brushes as they damage easily. A clean, dry linen cloth 
may be used. The commutator can be cleaned in a 
similar manner with the aid of a sharp wooden stick. 
This stick is used to force the cloth between the com- 
mutator segments. Under no circumstances should benzine 
or any cleaning fluid be used. 

d. possible trouble: 
tachometer reads low 

This can be evidenced by comparing the readings 
with a revolution counter. 

1. Cause and prevention. A low reading on the ta- 
chometer is caused by insufficient magnetic field. The 
magnetic field, through which the armature of the 
generator rotates, is produced by permanent magnets. 
As the pole strength of these magnets decreases, the 
field strength decreases with a decrease in voltage pro- 
duced. This will cause less voltage for a certain speed 
with a consequent lower speed indication than that 
actually being made. As the strength decreases, the 
error becomes greater. The magnet must then be 

2. Repair. To reenergize the magnet, it must first 
be removed from the generator. It can be drawn across 
the end of a coil magnet (iron core) that has a large 
current flowing through its coils. The polarity of the 
magnet must not be reversed when reenergizing it. 

344 # QsififtBiMWrPRINTING OFFICE: 1946—666202 


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